# Gas for BMW



## Pinecone (Apr 3, 2002)

Bob Clevenger said:


> Nah, I can't believe you are THAT insane. I'll bet that when you see that 18-wheeler blocking the whole road whilst backing into a driveway even you ease off the throttle a bit.  Yes, I've "been there, done that' when it comes to driving foe maximum fun and minimum fuel mileage -- I've outgrown it (mostly) now. No problem with the rest of you having fun, but really, you are not at WOT most of the time (unless you live out in the middle of a desert somewhere).
> 
> Have fun, enjoy your car(s). I know I do.


No I jusst get there BEFORE the 18 wheeler can get teh road blocked?

And then there is Stuka. Inspection 2 (yes TWO) in under 36K miles.


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## FenPhen (Jan 13, 2004)

mark07960 said:


> Basically, it makes no difference to the engine as to what octane is used, as these modern engines compensate electronicly for the differences in fuel burning characteristics.


Yes, the car can electronically compensate by adjusting timing, but it can't adjust its compression stroke (right?). Mechanically, it has to do the same thing, which always threatens premature detonation, but the car has to rely on electronics to spark sooner. This is like forcing someone to run on their toes or with a different stride.

http://www.bimmerfest.com/forums/showthread.php?p=1116959


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## Bob Clevenger (Dec 17, 2004)

FenPhen said:


> Yes, the car can electronically compensate by adjusting timing, but it can't adjust its compression stroke (right?). Mechanically, it has to do the same thing, which always threatens premature detonation, but the car has to rely on electronics to spark sooner. This is like forcing someone to run on their toes or with a different stride.
> 
> http://www.bimmerfest.com/forums/showthread.php?p=1116959


 Not logging in on either side of this issue (I think there is more to learn), however the variable valve timing can make the intake valve remain open later after BDC, thereby lessening the effective compression ratio. I don't know if the engine management computer actually does this or not, but it is definitely possible.


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## indyzhp (Mar 29, 2004)

*Late chime in!*

To add to the Costco info, one morning I was on my way in to work filling up at Costco and I saw a tanker with a BP logo filling the tanks. I have also noticed that the Costo stations in Indianapolis have a plaque that says "Gas contains 10% ethenol", whereas no other station I have been to around town says that except the BP stations. Any affiliation, or mere coincidence?


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## LDV330i (May 24, 2003)

indyzhp said:


> To add to the Costco info, one morning I was on my way in to work filling up at Costco and I saw a tanker with a BP logo filling the tanks. I have also noticed that the Costo stations in Indianapolis have a plaque that says "Gas contains 10% ethenol", whereas no other station I have been to around town says that except the BP stations. Any affiliation, or mere coincidence?


My understading is that even many branded stations get supplied by independent jobbers with "generic" gas but that brand specific additives are introduced at the delivery point.

So the Costco in your area may be getting BP refined gas but does not get any of the BP detergents/additives. This is critical for maintaining your valves and fuel injection system clean. You do in fact get what you pay for.


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## Greg220 (Mar 31, 2005)

Pinecone said:


> (...)
> 
> As for which additive package is "best." the answer is none of them. They all remove deposits, but they all make their own deposits. *So the best thing to do is to change suppliers every so often.* 2,000 - 5,000 miles is a good interval. This allows one additive package to remove the deposits from teh other, and no lay down too many of its own. But this does apply to name brand stations. Sheel, Exxon, Mobil, Texaco, Citgo, Sunoco, Crown, BP,etc. Not the no name ones that spot buy. You have NO idea what you are getting with them.


Does it have any negative effect to actually gas up at random brand-name station every time (Shell, week later Texaco, then Chevron etc), rather than gasing up at single one for X miles and then change the supplier?


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## gene2598 (Jul 10, 2004)

Most expensive gas I ever bought was from a gas station in TX that was located directly across the street from a refinery. AND YES, the gas station was the same company as the refinery.

AND, get this....You could see the supply pipeline from the refinery that went above the road and directly into the gas station. Most expensive gas in that town too.

Can't be a transportation cost issue.


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## Pinecone (Apr 3, 2002)

As for swapping every tank, the only problem I see with that is that if you haven't been doing this all along, it might not clear exisiting deposits. Also the cleaners take a few tanks to fully work. But the info I passed along was from a petroleum engineer, and I would think that he though of that. 

WRT generic gas, typically branded stations get their gas from branded suppliers, just not always their own brand. But you are correct, branded stations get a specific additive package for that brand that is added as the tanker truck is filled.

Generic stations get left over branded gas, non-branded gas, and mixtures of various stuff, and of course what is in the tank is a mix of various products. Tought to know what you are getting.


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## Ågent99 (Jan 7, 2002)

Pinecone said:


> No I jusst get there BEFORE the 18 wheeler can get teh road blocked?
> 
> And then there is Stuka. Inspection 2 (yes TWO) in under 36K miles.


Note to self: Don't buy a car Terry has driven....


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## iateyourcheese (Sep 9, 2004)

gene2598 said:


> Most expensive gas I ever bought was from a gas station in TX that was located directly across the street from a refinery. AND YES, the gas station was the same company as the refinery.
> 
> AND, get this....You could see the supply pipeline from the refinery that went above the road and directly into the gas station. Most expensive gas in that town too.
> 
> Can't be a transportation cost issue.


There has to be more to this than that. Maybe the employees get a discount so their main customers are still getting a good deal.

The data just doesn't support the "it's not transportation" hypothesis. Maybe it's in the additive package. How about this...

Gas is pumped throughout the US. At regional centers it is tanked and additives are added. Then it is trucked to the individual station. Maybe the extra cost comes in since they have to spend extra time to add the additives for just this one station.


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## Chupracabre (Mar 5, 2005)

My dad used to drive truck and one gig was him trucking gas.

The joke is that his truck went from gas station to gas station , regardless of Clark, Exxon, Chevron, Shell, BP, whatever.

It is the Octane reading you are interested in. 93 - 94 

As to the other post about additives - those vary from place to place and deal with the justification of why our gas is a penny more than the guy across the street.


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## FenPhen (Jan 13, 2004)

Chupracabre said:


> As to the other post about additives - those vary from place to place and deal with the justification of why our gas is a penny more than the guy across the street.


My uneducated theory is that the penny differences are a function of how much traffic one location gets versus another. (It does make a difference what side of the street you're on.)


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## BBBMW (May 1, 2005)

My 325Ci gets nothing but 91 Octane.....hates regular fuel


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## Pinecone (Apr 3, 2002)

Just to be correct, you do not buy pump gas by OCTANE in the US, you buy it by AKI (Anti Knock Index) which is an average of two OCTANE numbers. The RON (Research Octane Number) and the MON (Motor Octane Number) which differ as to test conditions. MON test conditions are harsher than RON, given a lower number for the same fuel. But there is no relationship between MON and RON for a fuel, it is what it is.


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## HughH (Jan 17, 2005)

When an auto manufacturer claims X number of MPG he has to commit his vehicle to a set of tests in order for his claim to be accepted by the EPA. Most of the time they will run the tests using the highest octain gas they can get in order to obtain the highest MPG and as a side result, higher HP. 
Higher numbers look GREAT to the marketing staff. The actual difference in your car usually cannot be perceived, depending in the car and load placed in the engine. In other words, driving around town, I have never felt any difference in power.

As to which brand is better...it's been many years since I saw a truck labeled Mobile. Exxon or whatever. It's usually some name that I cannot identify.

As for ingredients, the gas in our area must contain a certain percentage of MTBE. That makes the price of gas to go up, lowers the milage we get out of our cars and it has also been proven that it does nothing good for the air we breath!

Yeeears ago, Mobile was the only "certified" gas that passed the "BMW test". I wonder what happened since then. A reformulation of the gas or perhaps a change in marketing that caused a difference between the two companie$.


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## adventurelarry (Apr 6, 2005)

:dunno: I am more confused about gas than ever :dunno:


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## Pinecone (Apr 3, 2002)

HughH said:


> When an auto manufacturer claims X number of MPG he has to commit his vehicle to a set of tests in order for his claim to be accepted by the EPA. Most of the time they will run the tests using the highest octain gas they can get in order to obtain the highest MPG and as a side result, higher HP.
> Higher numbers look GREAT to the marketing staff. The actual difference in your car usually cannot be perceived, depending in the car and load placed in the engine. In other words, driving around town, I have never felt any difference in power.
> 
> As to which brand is better...it's been many years since I saw a truck labeled Mobile. Exxon or whatever. It's usually some name that I cannot identify.
> ...


1) Higher AKI does not provide higher mpg. Higher AKI only provides greater resistance to detonation. Higher AKI does not always provide more HP either. Higher AKI MAY, in SOME vehicles provide a bit more HP, but usually only under certain circumstances.

I am not sure that the AKI of the fuel is specified in SAE Net HP test protocol, but I suspect that it is, since the use of SAE Net is a backlash agasint very questional HP claims using the SAE Gross HP test.  It is likely done at the specified minimum AKI for the engine.

You will not feel the effect of higher AKI running around town, because there is no effect under most normal driving conditions, only during full throttle operation. At part throttle the engine is not operating at the limits, only at full throttle. If you could, you could run two fuel tanks in teh car, one for full throttle and one for running around, with cheap gas for part throttle, and the best gas for full throttle. Not really practical, but certainly doable.

2) The oil companies no longer own the delivery trucks. They found it is much cheaper to contract out to other comapnies or independent turckers to delivery the gas to stations. But the gas delivered to the brand name stations contains THEIR specific additive package. As for the comment about one truck delivering to mulitples taions, that is siple, the truck is not one big tank, it is several smaller tanks. Normally 2,000 gallons per segment. So a truck could be loaded with several different fuels based on AKI as well as additive package.

3) MTBE regulations are old. MTBE works by artificially leaning the mixture in cars that do not have active mixture control. Basically it made carbureted cars run leaner and cleaner. But those are pretty few and far between now, so all it does for us is lower the miles per gallon. BTW MTBE requirements change from season to season, so gas you buy in teh winter is more likely to contina more MTBE than gas bought in the summer.

As to being approved by BMW< it is based o nteh amount of type of cleaning agents. Most premium fuels contain plenty of good cleaners now, so it isn't as big a deal. BMW made a big deal about it due to significant valve deposits many years ago.

But over the years, I have found a tank or two of Mobil Super Premium to boost gas mileage by 1 - 2 mpg for a period of time, so their additive pacakge does seem to be more aggressive than others. But any brand company (Shell, BP, Mobil/Exxon, Citgo, Sunoco, etc) will do fine in your car.


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## HughH (Jan 17, 2005)

But over the years, I have found a tank or two of Mobil Super Premium to boost gas mileage by 1 - 2 mpg for a period of time, so their additive pacakge does seem to be more aggressive than others. But any brand company (Shell, BP, Mobil/Exxon, Citgo, Sunoco, etc) will do fine in your car.>>>
Terry,
A very informative answer, thanks.
Long time ago, that's exactly what I used to do, since it was the Premium of any brand the one that was "suppossed" to contain all the additives and it seemed you could tell the difference almost immediately when accelerating hard, at least with Mobile. In this area (DFW) most gas companies now advertise their "cleaning" properties for all three types of gas.

We are blessed to have a car guru that has a radio show every Saturday from 8-1PM (Central Time) on KLIF (available on the Internet), The question of what grade of gas to use almost always pops up every week. Ed Wallace, who has been on the auto industry for well over thirty years and who sometimes contributes to Car&Driver claims none of his cars have ever seen Premium gas for the last ten years or so. His present personal car now is the Acura RL. He recommneds Premium if you are looking into getting the maximum performance. Otherwise, save your money and stay with Regular.

Personally, the first time I ever heard of a car with "mapping" to allow for lower octain was the Audi 5000 back in '77 or '78 I think it was. At that time, most domestic cars were still using carbs, while most German/Sweedish cars were already into fuel injection.


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## Pinecone (Apr 3, 2002)

I would not recomend any lower AKI than the manufacturer recommends. You are bettin gon teh the mapping and knock sensor to deal with abnormal conditions. Not in my engines.


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## Pinecone (Apr 3, 2002)

Hmm,

Notice the difference in performance? So you spend $60K for a car based on its performance, then you throw it away to save the cost of a cheap car over 50 YEARS for 3 people?

BTW the average BMW fill up is more like 12 gallons. So that cuts your $30K to $18K over those 50 years for 3 people, or one econobox.

They also did not check economy changes. Premium fuel allows the ECU to run more ignition advance, which typically increases gas mileage. Which will wipe out even more of your savings.

As for driveability problems, that was over a fairly short term test. Try it day in day out over lots of weather conditions and you may not agree. Premium fules tend to have more detergent additives, which for a BMW is a good thing, or you can add some BMW fuel clenaer every few tanks, drivng up your overall fual costs.

Oh, and that nice 6year, 100K warranty, you have just voided it if BMW NA finds out you are running below the required AKI for the vehicle.

Yeap, great savings.


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## Moderato (Nov 24, 2003)

No one has mentioned HESS, is that pretty decent gas/addivtive?


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## Shabba (Feb 26, 2005)

Why has no one mentioned where the gas comes from i.e. The middle east, Venezuela, etc.? Difference or no? I personally would like to vote with my wallet insofar as which dirty bastard of a country gets my money! Does it make a difference in the price, quality or personal politics?


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## FenPhen (Jan 13, 2004)

redbeemer said:


> You save ten thousand dollars a lifetime per driver by using lower octane (ie better gas) than the manufacturer recommends without suffering any drivability problems (according to Car & Driver tests of an M3 on regular).


Decreased acceleration performance and decreased gas mileage does not count toward "driveability problems" anymore? :tsk: What about tires? Non-performance tires last tens of thousands of miles more than performance tires and are far cheaper. Might as well slum it with those too, right?


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## Bob Clevenger (Dec 17, 2004)

FenPhen said:


> Decreased acceleration performance and decreased gas mileage does not count toward "driveability problems" anymore? :tsk:


 When I hear the phrase "driveability problems" I don't think in terms of rate of accelleration or mpg. What I think of is "Does the car start easily?" and "In normal street driving does the car accellerate from a stop at a moderate pace smooothly and without noticeable hesitation?" and "Does the car stall easily and/or often?" IOW, is this car easy for the average driver to drive it in traffic?


> What about tires? Non-performance tires last tens of thousands of miles more than performance tires and are far cheaper. Might as well slum it with those too, right?


 That's a matter of driving style more than anything. If you race your car, high-performance tires are a definite benefit. If you primarily drive for transportation (even though you LIKE to drive -- that's why you don't drive a front-wheel drive econobox) and don't ever plan to race your car, then high-performance tires seem to be a waste of money. Isn't that why some of us have a set of "track tires"?

Sure, it's a real temptation to say: "Nothing but the best for my baby." but most of us do not have unlimited funds and need to make compromises. If a compromise actually harms the car, then that's a clear case of "Don't do it!" If a compromise only reduces a performance level that the driver never uses, that's a case of "An it harms none, do what ye will." And truly, most of us, no matter how good we think we are as drivers, and no matter how much we enjoy driving a responsive car, do not drive our Bimmers to their maximum ability. A few of us do (no, I'm not one of them).


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## Pinecone (Apr 3, 2002)

Shabba said:


> Why has no one mentioned where the gas comes from i.e. The middle east, Venezuela, etc.? Difference or no? I personally would like to vote with my wallet insofar as which dirty bastard of a country gets my money! Does it make a difference in the price, quality or personal politics?


No difference in teh car.

No way to tell bcause everyone gets crude from everywhere. Based on supply and price.


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## Pinecone (Apr 3, 2002)

Bob Clevenger said:


> When I hear the phrase "driveability problems" I don't think in terms of rate of accelleration or mpg. What I think of is "Does the car start easily?" and "In normal street driving does the car accellerate from a stop at a moderate pace smooothly and without noticeable hesitation?" and "Does the car stall easily and/or often?" IOW, is this car easy for the average driver to drive it in traffic? That's a matter of driving style more than anything. If you race your car, high-performance tires are a definite benefit. If you primarily drive for transportation (even though you LIKE to drive -- that's why you don't drive a front-wheel drive econobox) and don't ever plan to race your car, then high-performance tires seem to be a waste of money. Isn't that why some of us have a set of "track tires"?
> 
> Sure, it's a real temptation to say: "Nothing but the best for my baby." but most of us do not have unlimited funds and need to make compromises. If a compromise actually harms the car, then that's a clear case of "Don't do it!" If a compromise only reduces a performance level that the driver never uses, that's a case of "An it harms none, do what ye will." And truly, most of us, no matter how good we think we are as drivers, and no matter how much we enjoy driving a responsive car, do not drive our Bimmers to their maximum ability. A few of us do (no, I'm not one of them).


So you accept lower gas mileage and lower performance to save a few bucks? Then get rid of the M Coupe and be a Z3 1.9. Cheaper, cheaper insurance, burn sless gas, runs on regular as recommended.  Can't say much about XiT. 

The thing is, no one has done a long term test on lower AKI fuels to determine is there is any long term harm. BMW found that fuels with too low of an MON caused engine destruction, even with knock sensors and such on long high speed drives. While there is not direct coorelation between AKI andMON, you can figure that it isa bout 5 points less. BMW found that teh critcal number below 10 points below the RON. So a car rated for 91 AKI NEEDS 86 MON. So running it on 87 AKI (82 MON) may lead to long term engine damage, no matter what the controls. IS IT WORTH THE CHANCE?

Is it worth it for for a few grand over 50 YEARS?

WRT tires, the side benefit of higher performacne tires, even if you don't use the capability daily is that in you rdaily driving you are driving a much lower percentage of the cars total capability. This means in an emergency maneuver, you have more to get out of trouble, more to deal with changes in traction due to puddles, pavement changes, etc.

If you drive a 7/10th max of the ultimate of the car, by going to lower capability tires, you may redue the cars oer capability to say 8/10th of the ultimate. SO now your 7/10th driving is now almost 9/10th of the current capability. Not much headroom there.

I prefer to maximize the capability so give the most when I need it.

And the real reason for track tires is they last longer and don't go off like street tires do when pushed hard over several laps.

Your choice on these matters, just do it with the information needed to make areasonable decision.


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## HughH (Jan 17, 2005)

Pinecone said:


> I would not recomend any lower AKI than the manufacturer recommends. You are bettin gon teh the mapping and knock sensor to deal with abnormal conditions. Not in my engines.


Premium fuel is specified; lower octane is OK but power drops, BMW says>>>
Above quote from the USA Today review of the new 3 series. Enough said!


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## swchang (Oct 5, 2003)

I add Shell (or sometimes Mobil) 93. Every oil change (~6.5-7.5k miles) I add Techron to the fuel tank.


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## Bob Clevenger (Dec 17, 2004)

Pinecone said:


> So you accept lower gas mileage and lower performance to save a few bucks? Then get rid of the M Coupe and be a Z3 1.9. Cheaper, cheaper insurance, burn sless gas, runs on regular as recommended.  Can't say much about XiT.


 I'm not saying that I DO that. I'm just playing Devil's advocate here.


> The thing is, no one has done a long term test on lower AKI fuels to determine is there is any long term harm. BMW found that fuels with too low of an MON caused engine destruction, even with knock sensors and such on long high speed drives. While there is not direct coorelation between AKI andMON, you can figure that it isa bout 5 points less. BMW found that teh critcal number below 10 points below the RON. So a car rated for 91 AKI NEEDS 86 MON. So running it on 87 AKI (82 MON) may lead to long term engine damage, no matter what the controls. IS IT WORTH THE CHANCE?


 Absent any evidence to the contrary I would say "No." It is good to know that if you have no choice (runnin' on empty, gas station is out of premium) that you can fill up with whatever is available and be on your way without harming your engine.



> WRT tires, the side benefit of higher performacne tires, even if you don't use the capability daily is that in you rdaily driving you are driving a much lower percentage of the cars total capability. This means in an emergency maneuver, you have more to get out of trouble, more to deal with changes in traction due to puddles, pavement changes, etc.
> 
> If you drive a 7/10th max of the ultimate of the car, by going to lower capability tires, you may redue the cars oer capability to say 8/10th of the ultimate. SO now your 7/10th driving is now almost 9/10th of the current capability. Not much headroom there.
> 
> I prefer to maximize the capability so give the most when I need it.


 Just like having insurance, you hope never to need it, but if you do...



> And the real reason for track tires is they last longer and don't go off like street tires do when pushed hard over several laps.


Well, my original point is that those who DO race their cars don't use their track tires for everyday driving, even if they DO perform better than street tires. They suit their tools to the job at hand.



> Your choice on these matters, just do it with the information needed to make areasonable decision.


 Exactly.


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## FenPhen (Jan 13, 2004)

redbeemer said:


> In fact, there are dozens of MPG FAQs by the US Government stating you save money by buying "only the octane you need". (http://www.pueblo.gsa.gov/cic_text/cars/gas-save/gas.htm). Notice none of them say buy premium.


I gotta go to bed, but I clicked this link anyway. From the sound of your post, you trust what the government advises.

_There are numerous no- or low-cost steps you can take to combat rising gas prices. The most important place to start is at the gas pump; *buy only the octane level gas you need*. All gas pumps must post the octane rating of the gas under the FTC's Fuel Rating Rule. Remember, the higher the octane, the higher the price. *Check your owner's manual to determine the right octane level for your car.*_​


redbeemer said:


> However, the engineering boys at the FTC (http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm) tell me your assumption is baseless.


Clicked this one too.

_*Check your owner's manual to determine the right octane level for your car.* Regular octane is recommended for most cars. However, some *cars with high compression engines, like sports cars and certain luxury cars, need mid-grade or premium gasoline to prevent knock*.

How can you tell if you're using the right octane level? Listen to your car's engine. If it doesn't knock when you use the recommended octane, you're using the right grade of gasoline._​What they're assuming is you don't have a knock sensor. Try running your car without your knock sensor using non-premium fuel and tell me how your engine is doing. This was one of Pinecone's points, that if that knock sensor breaks, good luck.


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## Artslinger (Sep 2, 2002)

Wow this thread is something else. 

A few thoughts:

1. In my world the E46 runs better with the higher recommended gasoline.
2. Why would BMW recommend a higher octane gas if there was no benefit?
3. Never EVER believe anything the US government tells the public.
4. People paint themselves in a corner with stupid rational... and some will never budge no matter how wrong they may be.


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## Caesar (Apr 28, 2005)

redbeemer said:


> Everyone is entitled to their opinion and I respect yours.
> 
> Problem is, you provided no proof that running a BMW on 87 AKI gives lower gas mileage than on 91 AKI under normal driving conditions! In fact, the government says there's evidence of the opposite effect (http://www.fueleconomy.gov/feg/info.shtml). "Unless your engine is knocking, buying higher octane gasoline is a waste of money, too. "
> 
> ...


But none of that verbiage matters -- since the costs of 93 octane over 87 are not significant by any definition of the word.

Since it can't hurt to put in 93 octane -- and we are only talking a $.20 per gallon difference ($3.00 per tank, or $12.00 per month or $144.00 per year) -- it makes sense to use 93 octane (or 91 if available in your state).

For $144.00 per year, there is no reason to think about it. Just do it.

If the cost differences were more significant, than it would make sense to use 87.


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## Artslinger (Sep 2, 2002)

redbeemer said:


> My entire point is for us to think logically, with the big picture in mind, and with facts at hand. If none of bimmerfest verbiage matters & if you're already convinced your E46 runs "better", then you don't need to participate in this discussion of the NET economic, performance, & reliability of running 91 AKI vs 87 AKI in your BMW engine.


This thread is a discussion by ALL forum members on what type of gas is best to use in an E46, not about whether or not YOU think a higher octane is worth the extra expense.

And another thing where do you get off spewing words like "you're convinced" and "for us" or "then you don't need to participate in this discussion "&#8230; who the heck made you dictator of this forum.



redbeemer said:


> The whole purpose of this forum is to discuss economic/performance tradeoffs which might not be obvious to you or to me or to us or to anyone else.


The purpose of this forum is discuss all facets owning and driving a BMW not your person beliefs.


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## redbeemer (Mar 12, 2005)

Artslinger said:


> This thread is a discussion by ALL forum members on what type of gas is best to use in an E46, not about whether or not YOU think a higher octane is worth the extra expense.


OK. My mistake. No harm intended. When I used the word "forum" I didn't mean all of Bimmerfest. I meant this discussion specifically.

In this discussion titled "Gas for BMW", I thought we were outlining the technical & economic merits of running 91 AKI vs 87 AKI in our BMWs (separating proven fact from emotional fiction). By my listing the dozen engineering facets made in these discussions, I was simply summarizing the known test data and asking for a net conclusion from the users.

Since that's off topic, I will respect your wishes & delete my posts & reference material.
Sorry for misinterpreting your intent.

If I swayed the discussion I'm sorry. If, while presenting my arguments & facts, I came off as "appointing myself dictator of this forum", I'm more sorry. Best I sign out now.


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## Artslinger (Sep 2, 2002)

redbeemer said:


> OK. My mistake. No harm intended. When I used the word "forum" I didn't mean all of Bimmerfest. I meant this discussion specifically.
> 
> In this discussion titled "Gas for BMW", I thought we were outlining the technical & economic merits of running 91 AKI vs 87 AKI in our BMWs (separating proven fact from emotional fiction). By my listing the dozen engineering facets made in these discussions, I was simply summarizing the known test data and asking for a net conclusion from the users.
> 
> ...


I have no idea why you are taking this stand and deleting your posts I never requested that you pull your posts and do not appreciate you insinuating that I did. Just because you pulled some written material from somewhere doesn't make them proven facts and I found your posts emotional fiction like most posts in this thread so don't try and elevate your posts above others that may disagree with your opinions.

Varying points of view points make internet forums interesting reading but you may need a thicker skin if are willing to take a hard line stand on issues.

I hope this disagreement does not keep you from adding to this forum in the future.


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## Pinecone (Apr 3, 2002)

HughH said:


> Premium fuel is specified; lower octane is OK but power drops, BMW says>>>
> Above quote from the USA Today review of the new 3 series. Enough said!


Yeap, USA Today is the ultimate source.

You trust your car to lower AKI fuel and when your engine melts down, and BMW doesn't warranty it for using lower AKI fuel, remeber to try to sue USA Today.

Again, BMW has found that too low of MON octane rating on fuel has casued engine melt downs, even if the RON is higher enough, and despite the engine management controls. The problem occurs if the MON is lower than 10 points below the MON. For most pump fuel there is about a 10 point MON - ROM spread. So is the car requires 91 AKI by BMW, it needs a minimum of 86 MON to avoid melt down from long high speed runs. NO WAY 87 or even 89 AKI meets a 86 MON.


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## Pinecone (Apr 3, 2002)

Actually running too high of AKI can cause problems. It CAn cause lower fuel economy. But that is about it. But I agree, in todays market the difference in price is pretty low. Localy about the same 20 cents per gallon you quote. So to save the cost of a cheap car, you would have to run some 50,000 gallons of gas to save $10K.

Basically you should run the AKI recommended by the manufacturer, whoever that is. Higher is better than lower.


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## PKandCK (May 19, 2005)

I hate to say this, but you get what you pay for! It is true that gasoline is gasoline. What is not true is that they are not all equal. Unless you are buying from a branded outlet you are getting house grade gasoline with minimum additives. As an example, you may see a Chevron truck delivering to a Costco station, but the gas is not Chevron gas. It may have come from a Chevron refinery, but the additives are added at the rack. The gasoline is blended for the individual station at the rack were the truck picks up the gasoline. You will not find a top tier gasoline at a non-branded station. Also... proximity to the refinery or truck rack has no effect on price. It is strictly market based. (The dealer will get what his particular market will bare!) I am a supervisor at a top tier refinery... I pay more for gas across the street from the refinery that I do 40 miles away in my home town. Being the guy that actually makes the gasoline, watches the distillation process, watches the components being made and being aware of the different additive packages... I can tell you that I will only purchase top tier gasoline from branded gasoline stations. And most of the time it will be from the company I work for. (No, I do not get any employee discount and it is not Chevron) I will buy it from them because they are on the list of top tier gasoline manufacturers. And, you can find them on just about any street corner! 

Just my two cents.


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## PKandCK (May 19, 2005)

Also...
In regards to Clean and Envrionmentally Friendly refineries. Are you aware that there are more emissions to the atmosphere from dry cleaners in your local area than your local refinery? In CA, refineries are monitored very closely from local air districts. The refineries have what they call "Fugitive emission" programs. Every tubing connection, pipe flange and joint are routinely inspected for leaks in the 1 to 10 ppm range. If a leak is detected it must be repaired in 7 days or that particular piece of equipment must be shut down. 
Over the years refineries have gotten a bad reputation (rightfully so), however in recent times they have really cleaned up their act (excuse the pun). There has been much pressure put on them from regulation and public. They realize that they can not stay in business if they do not consider the planet first. I know of a refinery in CA that almost was put out of business because they were unable to operate in a safe manner. That refinery has since turned the corner and is doing very well. And by the way... one of the reasons gas prices are as high as they are is because of environmental mediation that must occur in the production of clean air burning gasolines...

Again, just my two cents.


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## vern (Apr 19, 2002)

Artslinger said:


> This thread is a discussion by ALL forum members on what type of gas is best to use in an E46, not about whether or not YOU think a higher octane is worth the extra expense.
> 
> And another thing where do you get off spewing words like "you're convinced" and "for us" or "then you don't need to participate in this discussion "&#8230; who the heck made you dictator of this forum.
> 
> The purpose of this forum is discuss all facets owning and driving a BMW not your person beliefs.


Lighten up and get on with the discussion.I find it very intresting that some people would rather put in 87 octane in there car and forget about what is recommended by BMW no matter what can happen to there ride.
cheers
vern


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## shaftdrive (Mar 10, 2005)

*Gas spoils in a month according to CR*

To help others, I post these URLs I found while I was looking up how long it actually takes gasoline to "spoil" in our tanks.

Notice Consumer Reports indicates gas may "spoil" after one month in the tank in this url http://xs.to/xs.php?h=xs42&d=05333&f=gasoline.gif

This thread indicates that the "spoiled" 1-month old gasoline begins to burn "better" (i.e., more spontaneous combustion under heat & pressure, aka lower octane rating) as it continues to "spoil" ... http://groups-beta.google.com/group/rec.autos.tech/browse_frm/thread/385772cf05dd4653?scoring=d&

And these references more clearly explain "octane" in more than a word like I used above (single words like "better" or "worse" can never be wholly accurate when talking about octane ratings but I can't put the entire dissertaion on octane in this so I use better/worse for lack of a better single word description for how the gas burns differently over time).
http://chemistry.about.com/cs/howthingswork/a/aa070401a_2.htm
http://autorepair.about.com/od/enginefuelgasolines/a/highoctanegas.htm
http://www.repairfaq.org/filipg/AUTO/F%5FGasoline6.html

Lastly, these Bimmerfest URLs provide more details on octane ratings (but not spoiling of the gasoline which seems to occur in a longer period of time than Consumer Reports alludes to by most posts on rec.motorcycles and rec.autos.tech).

http://www.bimmerfest.com/forums/showthread.php?t=38833
http://www.bimmerfest.com/forums/showthread.php?t=55737
http://www.bimmerfest.com/forums/showthread.php?t=98642
http://www.bimmerfest.com/forums/showthread.php?t=98055

I post this to help others realize:
- Gas apparently spoils more quickly than I realized (1 month according to CR).
- When it spoils, it begins to burn "better" (i.e., the AKI goes down, not up!)

Wierd. Not intuitive. But that's what the URLs above seem to indicate.


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## Krochelli (May 9, 2005)

PKandCK said:


> I hate to say this, but you get what you pay for! It is true that gasoline is gasoline. What is not true is that they are not all equal. Unless you are buying from a branded outlet you are getting house grade gasoline with minimum additives. As an example, you may see a Chevron truck delivering to a Costco station, but the gas is not Chevron gas. It may have come from a Chevron refinery, but the additives are added at the rack. The gasoline is blended for the individual station at the rack were the truck picks up the gasoline. You will not find a top tier gasoline at a non-branded station. Also... proximity to the refinery or truck rack has no effect on price. It is strictly market based. (The dealer will get what his particular market will bare!) I am a supervisor at a top tier refinery... I pay more for gas across the street from the refinery that I do 40 miles away in my home town. Being the guy that actually makes the gasoline, watches the distillation process, watches the components being made and being aware of the different additive packages... I can tell you that I will only purchase top tier gasoline from branded gasoline stations. And most of the time it will be from the company I work for. (No, I do not get any employee discount and it is not Chevron) I will buy it from them because they are on the list of top tier gasoline manufacturers. And, you can find them on just about any street corner!
> 
> Just my two cents.


This might all be true, but I have not noticed a performance or mpg difference by using Costo 91 octane gas, and I haven't seen a test posted.

I would be curious if others have?


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## LDV330i (May 24, 2003)

Using the right octane is only half the story. You should also use gas that has the right detergents and additives such as Chevron, Shell, etc. Do a search on Top Tier and you will find a listing of BMW approved gas. Yes, such list does exist and Costco is not on that list.


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## Artslinger (Sep 2, 2002)

LDV330i said:


> Using the right octane is only half the story. You should also use gas that has the right detergents and additives such as Chevron, Shell, etc. Do a search on Top Tier and you will find a listing of BMW approved gas. Yes, such list does exist and Costco is not on that list.


Just because some companies are not on that list does not mean they are not a good gas for a BMW, some companies have declined to be on the "Top Tier" for reasons other than not being able to match or excide those standards set buy "Top Tier".


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## shortyb (Dec 5, 2004)

Gasoline brands on the "Top Tier" list are those that meet the detergency additive criteria for ALL grades of fuel that particular retailer sells. There are others such as BP (Amoco) that deliver/exceed these levels in their 93 but not in their 87 & 89 grades. Thus, BP is not listed, but Amoco 93 is a highly rated fuel.


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## Artslinger (Sep 2, 2002)

The "Top Tier" brands are companies that meet the "Top Tier" standards and agreed to be on the list, there are brands that meet the standards but have chosen not to be on the list probably because they do not like car manufactures setting gasoline standards. 

Top Tier can't but a brand on the list without that company’s permission; really it is just another marketing gimmick, IMO. 

Choosing a Top Tier company's gasoline can assure you that it exceeds the EPA detergent additives standards.


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## Salvator (Oct 14, 2003)

shortyb said:


> There are others such as BP (Amoco) that deliver/exceed these levels in their 93 but not in their 87 & 89 grades. Thus, BP is not listed, but Amoco 93 is a highly rated fuel.


I have recently experimented with using only BP (Amoco) 93 octane gas in my 325Ci, and in my unscientific opinion, it has made an improvement in how my vehicle performs (aceleration, specifically) and also in my gas mileage... Coming home last night, I checked my MPG for the tank, I was getting 29 MPG... I have routinely seen mid-27s and the occassional 28 MPG... I drive approximately 65% Hiway, 35% City... Previously, I was getting consistent 26 MPG over the same commute, with other brands of gas... If I consistently get 28MPG with BP, versus 26 MPG with other brands, I am effectively getting an extra gallon with every fill-up!


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## Krochelli (May 9, 2005)

LDV330i said:


> Using the right octane is only half the story. You should also use gas that has the right detergents and additives such as Chevron, Shell, etc. Do a search on Top Tier and you will find a listing of BMW approved gas. Yes, such list does exist and Costco is not on that list.


Like I asked, can I see some proof it helps performance?

My grandfather was a petroleum engineer for Texaco for 40 years. Heck, he was on the unleaded fuel commission in the 70s even but still always uses Texaco or Exxon, as he felt both were by far the best gas on the market. Exxon isn't even on the list.


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## swchang (Oct 5, 2003)

Krochelli said:


> Like I asked, can I see some proof it helps performance?
> 
> My grandfather was a petroleum engineer for Texaco for 40 years. Heck, he was on the unleaded fuel commission in the 70s even but still always uses Texaco or Exxon, as he felt both were by far the best gas on the market. Exxon isn't even on the list.


Please read both of Artslinger's comments above.


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## gbelton (Aug 3, 2003)

*If I Were a BMW*

Hello My Friends:

I appreciate the Gas/Petrol conversation; in fact, I find it very entertaining.

Fact: Unless you are a car Engineer/Manufacture with the base facts as to what runs best in our BMers; hell, why are we so challenged to take under advisement that if you buy a premium vehicle you need to use premium fuel. Come on ladies and gentlemen...

I guess it boils down to the following: If you care enough to spend your dollar on a premium vehicle, in this case a BMer. Why don't you take the natural step to ensure the care and feeding of such a rarity in vehicle design and mechanics?

Don't treat me that way because if I were a BMW, I would only expect the best from you. Thank you for taking the drive and I will see you at the gas pump!

"Filler up, 93 PLEASE!" :thumbup:

-GMAN


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## Krochelli (May 9, 2005)

*Costco*

Here is Costco's reply :

Gasoline is a pure commodity, as the government requires specific gasoline
formulations that all refineries must meet. Those formulations change
within different areas of the country depending on air quality, but all gas
sold in a particular area must be the same. The only difference between
brands is the detergent additive package. The Federal government has
required EPA-approved detergent additives in all fuel since 1995.

Additives are added to the gasoline when the tanker truck is filled before
delivering to retail stations. So regardless of who produces the gasoline,
it's the additive that brands it. The fuel Costco buys, either under
contract or on the open spot market, receives a generic additive package
that meets the EPA requirement. We do not sell fuel with a branded, and
thus proprietary, additive package.

Thanks,

Tim Hurlocker
Director of Gasoline Operations
Costco Wholesale, Inc.


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## gbelton (Aug 3, 2003)

*And....*

Hello My Friends:

:tsk: Way Uncool :tsk: but thanks for the disclaimer.

-GMAN


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## Pinecone (Apr 3, 2002)

shaftdrive said:


> And these references more clearly explain "octane" in more than a word like I used above (single words like "better" or "worse" can never be wholly accurate when talking about octane ratings but I can't put the entire dissertaion on octane in this so I use better/worse for lack of a better single word description for how the gas burns differently over time).
> http://chemistry.about.com/cs/howthingswork/a/aa070401a_2.htm
> http://autorepair.about.com/od/enginefuelgasolines/a/highoctanegas.htm
> http://www.repairfaq.org/filipg/AUTO/F%5FGasoline6.html


Reference 1: Incorrect. Pumps are labeled with AKI (Anti Knock Index) NOT a "octane" rating, in the US. It is the average of two octane rating specficications. RON and MON differ by a whole lot more than RPM. Also intake air temperature, oil temperature, cylinder head temperature.

Straight run gasoline is somewhat a misnomer. There is no chemical that is gasloine, it is made up of many different hydrocarbon molecules, and everything is hydrocracked or otherwise messed with during the distillation process to prouce more of the molcules in gasoline that were present in the original crude oil. This to increase yeild of gasoline.

Reference 2: Many wrong things. Knocking is NOT premature ignition, that is pre-ignition. Knokcing as stopped by octane is DETONATION, a very different situation. Pre-ignition comes from the charge igniting prior to the spark plug firing. Detonation happens after the spark plug fires.

Running a higher AKI than specified, in a modern car, actually may help performance, since under certain circumstances, even with the proper recommended AKI can start to detonate and cause the timing to be reduced (and boost reduced on turbo or supercharged cars) reducing power. So by running a higher AKI you can get more power in some circumstances. Also,m some cars (E46 M3) do produce more power up to a higher AKI than minimum spec. The E46 M3 benefits with up to 96 AKI fuel.


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## Rich_Jenkins (Jul 12, 2003)

Been following this thread off and on for a few days as my tank empties.

I found the top tier web site the other day, and happened by a Chevron station this afternoon with the fuel light on and 23 miles showing on the countdown :eeps:.

(BTW, this station is located near UCF on Alafaya Trail and University Blvd, and is a total dump. 50% of the pumps were baggied off, the paint was peeling in strips from the overhead and the pump apparatus was used and abused. Not much of a statement for Chevron I am thinking.)

Anyway, I filled up with a tank of 93 octane, $42.14 for 15.442 gal at $2.729 per.

We'll see how it runs from here...


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## LDV330i (May 24, 2003)

wingspan said:


> Been following this thread off and on for a few days as my tank empties.
> 
> I found the top tier web site the other day, and happened by a Chevron station this afternoon with the fuel light on and 23 miles showing on the countdown :eeps:.
> 
> ...


Please note that Texaco and Chevron are one and the same. I filled up yesterday with Texaco gas advertised now to have Techron.


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## Rich_Jenkins (Jul 12, 2003)

LDV330i said:


> Please note that Texaco and Chevron are one and the same. I filled up yesterday with Texaco gas advertised now to have Techron.


Thanks, I'll keep that in mind. I also noticed a Sunoco just next to our local grocery store, so that'll be convenient too...


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## FingerTight (Feb 13, 2004)

So yeah, *my .02$*

1) Knock sensors are a safety to save your engine (ie: bad mix o' gas), do you park with your bumpers? :eeps:

2) Octane is a measure of a fuel's volatility, higher octane = less "explosion" and a more even burn. The less "explosive" a fuel is, the less it is likely to experience uncontrolled detonation. Compression, timing, etc can increase the possibility of uncontrolled detonation and, hence, require the higher octane.

3) Unless one is experiencing detonation, higher octane will actually yield less power due to a decrease in the "explosion" on the power stroke.

4) I would imagine that modern electronic control can allow for taking advantage of a little extra octane by advancing timing. Noticeable? Hardly. Would a company do this sort of timing advance past the recommended octane? Yeah right!

4) I have always thought "knock" "ping" "pre ignition" "detonation" etc were all the same. Can someone go into more detail as to the differences, if there are any?

5) If we are talkn about an extra $150 a *YEAR*, who gives a s***, put in the premium man!

My conclusion: Just use what the manufacturer reccomends. Don't go less, don't go more, no extra addatives, etc etc. These guys spent oodles of cash engineering this thing, they know it better than any of us will ever know it, I tend to want to listen to 'em. :angel:

So there is my opinnion, thanks for listenin'


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## Pinecone (Apr 3, 2002)

1) EXACTLY

2) Wrong, octane is a measure of the fuels ability to resist detonation. ONLY. Higher octane does not reduce power, reduce force, burn slower, have less "explosion" etc.

3) Wrong, see above.

4) Yes, and in some cases of air temp, humidity etc, even with the rated AKI fuel, your engine will reduce power to avoid detonation.

4) Nope. Pre-ignition means teh fuel-air charge ignites before the spark plug fires. Detonation occurs after the spark plug fires, and is a result of excessive heat and pressure in teh combustion chamber causing spontanteous combustion in various parts of the cylinder leading to multipe flame fronts and even high pressures. Normal process is the combustion chamber is acontrolled burning of the fuel to evenly increase pressures. Knock or ping is the symptom that drivers hear. Etierh pre-ignition or detonation can cause knock or ping, but higher octane only fixes detonation.

5) Exactly.


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## Bob Clevenger (Dec 17, 2004)

FingerTight said:


> So yeah, *my .02$*


OK, here's how I understand it. YMMV 



> 1) Knock sensors are a safety to save your engine (ie: bad mix o' gas), do you park with your bumpers? :eeps:


I partly agree. Knock sensors are partly a "safety valve" as you say, and partly an engineering tool that allows an engine to be designed at a high state of tune that would otherwise cause it to knock badly under normal street conditions. I once had a '70 Dodge Challenger R/T with an "almost stock" :rofl: 440 six-pack engine. It was running about 11.5 to 12.0 to 1 compression. I had to de-tune it (read retard the ignition) severely to get it to run on premium pump gas without knocking at low speed-high load conditions --- such as starting from a stop. With modern knock sensors that engine could have retarded it's own ignition when starting out and still be tuned for power at high rpms.



> 2) Octane is a measure of a fuel's volatility, higher octane = less "explosion" and a more even burn. The less "explosive" a fuel is, the less it is likely to experience uncontrolled detonation. Compression, timing, etc can increase the possibility of uncontrolled detonation and, hence, require the higher octane.


Right conclusion, but wrong definition of 'octane'. Octane rating has absolutely nothing to do with volatility. Volatility is the measure of how easily a liquid evaporates. Octane rating is a measure of how rapidly a fuel burns. An research octane rating of 100 means that the fuel in question burns at the same rate as a particular hydrocarbon known as 'iso-octane' which is chemically (CH3)3CCH2CH(CH3)2.



> 3) Unless one is experiencing detonation, higher octane will actually yield less power due to a decrease in the "explosion" on the power stroke.


Actually gasoline does not explode in an IC engine unless something is wrong . It is a controlled burn. Yes, a higher than needed octane rating will produce slightly lower power due to lower energy density. Raising the octane rating has it's price (and not just at the pocket book :bawling: ).



> 4) I have always thought "knock" "ping" "pre ignition" "detonation" etc were all the same. Can someone go into more detail as to the differences, if there are any?


'Knock' and 'ping' both refer to combustion that is either too fast or too soon. 'Ping' is usually minor and not terribly damaging in small doses --- backing off on the timing will usually cure it; 'knock' is usually more severe and may not be so easily fixed. "Pre-ignition' usually means that the fuel-air charge is igniting before the spark. Could be due to carbon build-up in the cylinder head, or other "hot spots" that retain enough heat between strokes toignite the fuel-air mixture. An overly-lean mixture can also cause this. 'Detonation' is bad news; the fuel-air charge burns so fast that it is nearly an explosion. This can put holes in the tops of pistons! Combine this with timing that is too far advanced and you have a recipe for a new engine.



> My conclusion: Just use what the manufacturer reccomends. Don't go less, don't go more, no extra addatives, etc etc. These guys spent oodles of cash engineering this thing, they know it better than any of us will ever know it, I tend to want to listen to 'em. :angel:
> 
> So there is my opinnion, thanks for listenin'


Yep, it's nice to know that we have things like knock sensors to cover our a--es if we are forced to use lower-octane fuel once in a great while. As far as additives go, all gasolines have them, they all are different with pluses and minuses, and I agree with others here who have advised us to change brands every so often so as not to let them build up their own deposits.

I am not a Chemical Engineer, nor do I play one on TV. I just remember some of this stuff from my college chemistry classes.That and reading every hot rod magazine I could get my hands on. :dunno:


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## zentenn (May 20, 2005)

Nice work Bob :bow:


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