# What kind of gas can I get away with?



## Alexis24 (Feb 26, 2011)

So, I'm on week 2 of *leasing *my first 128i. I've read a bit elsewhere on the forums, but am hoping someone can help me with a straight, simple answer.

*I'm trying to find out the least expensive longterm fuel option that won't cause engine issues for the 3 years that I lease the car.*

When I asked my salesperson she said the following: 
"If you fill with regular gas, make sure the next fill up is premium."

The manual says the following:
- Super Premium (91) is recommended, however you can also use a minimum of 87 AKI. 
- Use high-quality brands. 
- BMW recommends BP fuels. (Although I found that strange, as BP wasn't on the Top Tier Detergent Gasoline list)

So this leads me to additional questions, such as:
- If I use one gas station religiously that has the same detergent/additives, etc... can I just put in regular with occasional premium?
- Is the gas mileage that much better with premium that it justifies the increased cost?
- Will my car hate me if I put in regular gasoline from a crappy gas station brand?

Thanks!


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## Norm37 (Jun 28, 2008)

A fairly long read, but a lot of good info.

http://www.vettenet.org/octane.html


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## 02BMW530 (Nov 19, 2010)

It's a lease.... Why do you care? 

Just use premium at big-name stations. Go to BPs, Speedways, etc. Avoid places like "Johnnyz Finest" and such. 

Just use common sense. 

I switch stations quite regularly, but I always use premium. As far as I'm concerned, I can't see why you'd go to a gas station and NOT pump premium. And don't say cost; a 20 gallon tank is a $4 difference. 

It's just gas, you're looking too deep into this. 

Sent from my iPhone using BimmerApp


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## SD ///M4 (Jan 24, 2011)

Why would you lease a BMW and then cheap out by trying to buy the cheapest gasoline possible? You didn't know before you bought the car that it requires premium gasoline? It's not the issues that you'll experience during the short three years that you own the car, it's the longer term issues that will arise long after you've gone on to your third or fourth BMW, unfortunately for the poor CPO owner who didn't know you put crappy gas in it.

Why try to outguess the engineers that designed the engine? They're probably a lot smarter than you are. If they recommend super premium (91 octane) then that's what you should use. Are you going to also overinflate your tires by 10 psi to try and get longer life from your tires? Turn off the engine while coasting downhill to increase you mileage? If you can't afford the premium gas you shouldn't have bought the car.


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## jordan16j (Mar 7, 2011)

I agree no reason to cheap out on gas. If an extra $4 a tank for premium fuel is a deal breaker for you then you should be looking at a different mode of transportation . 

Sent from my ADR6300 using Bimmer App


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## TRS550 (Jan 2, 2010)

SD 335is said:


> Why would you lease a BMW and then cheap out by trying to buy the cheapest gasoline possible? You didn't know before you bought the car that it requires premium gasoline? It's not the issues that you'll experience during the short three years that you own the car, it's the longer term issues that will arise long after you've gone on to your third or fourth BMW, unfortunately for the poor CPO owner who didn't know you put crappy gas in it.
> 
> Why try to outguess the engineers that designed the engine? They're probably a lot smarter than you are. If they recommend super premium (91 octane) then that's what you should use. Are you going to also overinflate your tires by 10 psi to try and get longer life from your tires? Turn off the engine while coasting downhill to increase you mileage? If you can't afford the premium gas you shouldn't have bought the car.


+1. Seriously.


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## AzNMpower32 (Oct 23, 2005)

The German owner's manual states the following (and has done so for a decade):

98 RON (93 AKI in the US) is recommended for the advertised power and efficiency.
95 RON (91 AKI) is also acceptable. This is the minimum for the N54 turbo engine.
91 RON (87 AKI) is the absolute minimum for non-turbo engines.
Diesel that meets DIN 590 standards is sufficient. (Diesel models)
The *quality* of the fuel is extremely important. BMW writes more words on quality than octane.

In the US, our fuel isn't as clean or nice as that found in the EU, plus its got 10% Ethanol, so playing it safe, BMW probably states the 91 AKI requirement. It's your choice what you put in your car.


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## 02BMW530 (Nov 19, 2010)

So I can use diesel? Sa-weet! 

Sent from my iPhone using BimmerApp


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## BeemerMikeTX (Jun 6, 2010)

Thanks for reminding me why I don't buy ex-lease cars. :tsk:


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## Yorgi (Mar 17, 2005)

BeemerMikeTX said:


> Thanks for reminding me why I don't buy ex-lease cars. :tsk:


+1000

The car will retard the timing if you use regular gas which will result in less mileage. The $ savings by using regular gas just about even out with the loss in mileage due to drop in power.


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## 02BMW530 (Nov 19, 2010)

BeemerMikeTX said:


> Thanks for reminding me why I don't buy ex-lease cars. :tsk:


Ditto. And ex-rentals.

Sent from my iPhone using BimmerApp


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## George Allan (Feb 22, 2008)

*use 91 octane or not*

You may not notice much difference but the motor will. Not fair for the next buyer so I hope you care for your fellow man.

George Allan


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## Hot Toddy (Nov 23, 2010)

I read the article referenced above on gasoline and additives and learned a lot. I will try to switch brands in the future.

I always run premium in my car, but sadly to say, I really buy gas at whichever station has the best carwash. It is just so convenient for me to get fuel and a carwash at the same place. I should start going to a stand alone touch free carwash and then do a better job of switching between gas brands.

Hoy Toddy


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## AnonCA (Oct 26, 2010)

I'd get the cheapest gas possible. It will save you between 2 and 4 dollars a week.


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## Ryan... (Dec 16, 2008)

I love these threads....

I'm a 22 year old broke college student, driving a $2k car, while paying for everything I want and own. If I can afford to buy premium fuel, you sure as hell can too.


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## Bremen Ben (Sep 1, 2008)

If you can afford to drive a brand new BMW, you can afford the few buck difference in gas. Get premium.


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## djfitter (Sep 12, 2007)

Bremen Ben said:


> *If you can afford to drive a brand new BMW, you can afford the few buck difference in gas.* Get premium.


 Statements like this suck. How do you know the situation? :tsk:

dj


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## 02BMW530 (Nov 19, 2010)

djfitter said:


> Statements like this suck. How do you know the situation? :tsk:
> 
> dj


If you're paying $450/mo lease payments, what's $15 (max) extra in gas?

Sent from my iPhone using BimmerApp


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## Ryan... (Dec 16, 2008)

djfitter said:


> Statements like this suck. How do you know the situation? :tsk:
> 
> dj


He may not know the exact situation, but if the guy was so poor that he cant drop another $6 a tank he should not be spending $400 or more per month to rent a car :tsk:


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## djfitter (Sep 12, 2007)

02BMW530 said:


> If you're paying $450/mo lease payments, what's $15 (max) extra in gas?
> 
> Sent from my iPhone using BimmerApp


For all we know, it's money for food or diapers. Maybe there was a change in work hours. :dunno:

dj


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## djfitter (Sep 12, 2007)

Ryan... said:


> He may not know the exact situation, but if the guy was so poor that he cant drop another $6 a tank he should not be spending $400 or more per month to rent a car :tsk:


Nice of you to make that choice for him/her. :tsk:

dj


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## Ryan... (Dec 16, 2008)

djfitter said:


> Nice of you to make that choice for him/her. :tsk:
> 
> dj


Are you really going to argue that my point is not valid? Why spend big bucks on a nice car, only to skimp out on such a cheap, simple, yet necessary detail?

I understand looking for ways to save money, I do it all the time. How I go about it though, is completely different. I find quality parts for cheaper, find friends to help me work on repairs, possibly buy a cheaper brand of tires that will get me from A-B rather than the stickiest, top of the line brand, etc.. But $15 worth of gas that could potentially damage the car? C'mon...


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## djfitter (Sep 12, 2007)

Ryan... said:


> Are you really going to argue that my point is not valid? Why spend big bucks on a nice car, only to skimp out on such a cheap, simple, yet necessary detail?
> 
> I understand looking for ways to save money, I do it all the time. How I go about it though, is completely different. I find quality parts for cheaper, find friends to help me work on repairs, possibly buy a cheaper brand of tires that will get me from A-B rather than the stickiest, top of the line brand, etc.. But $15 worth of gas that could *potentially damage the car?* C'mon...


The manual says the following:
- Super Premium (91) is recommended, however *you can also use a minimum of 87 AKI. 
*
Damage? :bs:

Don't get me wrong here, I buy/use/recommend premium to get all the power I can especially since California doesn't have 93 octane. I find fault with the attitude some have and the thinking that they know how someone else can/should spend money while knowing NOTHING about the situation. I find it a bit arrogant. Maybe everything else has been done to save money and this is all that is left to them. Gas prices have gone up.

dj


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## w2 (Apr 29, 2008)

02BMW530 said:


> If you're paying $450/mo lease payments, what's $15 (max) extra in gas?


Isn't part of the issue that 87 octane doesn't actually save you money because the engine will perform less efficiently? In addition to causing premature engine wear and lower power output, using 87 instead of 91 means lower cost per fill-up, but more fill-ups, resulting in, at the end of the day, paying the same overall price for a lower-quality overall product.

The car can run with 87, meaning that if you accidentally fill it with 87 octane, or if you're stuck somewhere where that's all that is available, you will still be able to drive the car and not do serious damage to it, but trying to save money by using 87 all the time, even if the car is a lease and you don't care about the next owner or anything else that doesn't directly affect you personally, you are probably making a fool's bargain because, as is often the case, the cheapest price does not always work out to be the lowest cost.

Half-assed measures intended to save a few dollars often have the opposite effect, in addition to the negative consequences of going with an inferior-quality solution. On the other hand, most people can probably save at least 5-10% off their fuel bill simply by being more intelligent about where, when, and how much they drive. Planning your schedule so that you make fewer trips and do more on each one can save you both time and money, without compromising quality or the health of your vehicle.


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## Bremen Ben (Sep 1, 2008)

djfitter said:


> The manual says the following:
> - Super Premium (91) is recommended, however *you can also use a minimum of 87 AKI.
> *
> Damage? :bs:
> ...


If one is asking for opinions, then one should be expected to hear ALL opinions. What I said is one of those opinions.

What I find hard to understand is people who are willing to drop a significant sum of money on a luxury car like BMW, yet skimp on the minor things such as gas. I don't pretend to know everyone or anyone's circumstance, but there is frugality and then there is affordability. If 4 or 6 dollars more of gas money a month is grave enough to be one's concern in finance, then leasing a luxury car would seem like a contradictory choice. It's like buying a multi-million dollar mansion and then trying to save on heating bills by keeping the room temperature below comfort level. Do you get the house just to show people you have the house, or do you get the house because you can truly enjoy it?


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## twistediron (Mar 3, 2011)

02BMW530 said:


> Ditto. And ex-rentals.
> 
> Sent from my iPhone using BimmerApp


hah I don't get ex rentals and lease cars because of the fecal matter pubic hair and blood splatter.. thank you top gear for confirming my viewpoints


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## djfitter (Sep 12, 2007)

Bremen Ben said:


> *If you can afford to drive a brand new BMW, you can afford the few buck difference in gas.* Get premium.





Bremen Ben said:


> If one is asking for opinions, then one should be expected to hear ALL opinions. What I said is one of those opinions.
> How does this opinion relate to *any* of the questions asked by the OP?
> What I find hard to understand is people who are willing to drop a significant sum of money on a luxury car like BMW, yet skimp on the minor things such as gas. I don't pretend to know everyone or anyone's circumstance, but there is frugality and then there is affordability. If 4 or 6 dollars more of gas money a month is grave enough to be one's concern in finance, then leasing a luxury car would seem like a contradictory choice. *It's like buying a multi-million dollar mansion and then trying to save on heating bills by keeping the room temperature below comfort level.* Do you get the house just to show people you have the house, or do you get the house because you can truly enjoy it?


With this analogy, you are again imposing your views on other peoples spending habits instead of sticking to answering questions about the saving of money and doesn't make sense anyway, as the house is an appreciating asset, and if it can be purchased by scrimping and saving, what is wrong with that? The OP never said anything about *having* to save the money in question, only what was the least expensive option and whether it would harm the car. Oh yeah, also if the car would hate them. 
That's okay though, you have your opinion on saving money and I have mine. Oh wait, your opinion was chastising peoples choice of spending and had nothing to do with the questions asked.

dj


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## Andrew*Debbie (Jul 2, 2004)

*Answering the OPs questions*



Alexis24 said:


> straight, simple answer
> 
> - If I use one gas station religiously that has the same detergent/additives, etc... can I just put in regular with occasional premium?


Yes. Performance and gas mileage are both lower on regular.



> - Is the gas mileage that much better with premium that it justifies the increased cost?


It depends on how you drive and difference in price.

The difference in cost is small. -- Example. All in US gallons. (I live in the UK where gallons are bigger) Regular is $3.60/gal and premium is $3.70/gal ( I got ballpark prices from here --http://www.newjerseygasprices.com/GasPriceSearch.aspx?fuel=A&qsrch=Elizabeth,%20NJ )

You drive 12,000mi a year. You get 22mpg on regular and 23mpg on premium. This is reasonable for a 128i but YMMV.

In a year would use 545.45gal of regular or 521.74gal of premium

A year's worth of premium would cost $1930. A years worth of regular would cost $1963.

If you got 23mpg on both regular and premium or 521.74 gallons. -- A year's worth of premium would still be $1930 and regular would be $1878. *That's less than $5/month.*



> - Will my car hate me if I put in regular gasoline from a crappy gas station brand?


No, its a car. You may hate yourself if you keep the car past the end of the lease. You will hate yourself a lot sooner than that if the crappy brand fuel has more than 10% ethanol.


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## djfitter (Sep 12, 2007)

Andrew*Debbie said:


> Yes. Performance and gas mileage are both lower on regular.
> 
> It depends on how you drive and difference in price.
> 
> ...


Andrew*Debbie thank you for getting it. :thumbup:

dj


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## mujjuman (Feb 2, 2009)

You lease a $30,000 BMW and will probably drop close to $15,000 in payments... how can you not afford to pay $5.50 more per tank?! 

It's a 128, it will handle the 87 just fine. But do you really want a lower performing engine? Not to mention 87 is usually cheaper quality gas compared to 91/93.


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## S93D (Apr 24, 2008)

Yorgi said:


> +1000
> 
> The car will retard the timing if you use regular gas which will result in less mileage. The $ savings by using regular gas just about even out with the loss in mileage due to drop in power.


Not true.

Power is subjective and a desire. How much it is worth is a personal decision.

Gas mileage is just dollars and cents. Premium gas will not result in sufficiently better gas mileage to pay for the increased cost. It will offset it slightly, though. I did some calculating before and I think it was roughly if gas were $5/gallon, premium should cost about 8 cents or so more expensive to justify the better mileage. If it is 20 cents more, it is not worth the cost.

Having said that, I use premium. It is because the X3's automatic transmission is picky. If I use premium, when I go up a certain hill, it hunts much less if I use premium on a regular basis. Most people don't drive up that certain hill.


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## Tom K. (May 10, 2008)

S93D said:


> Not true.
> 
> Power is subjective and a desire. How much it is worth is a personal decision.
> 
> Gas mileage is just dollars and cents. Premium gas will not result in sufficiently better gas mileage to pay for the increased cost. It will offset it slightly, though. I did some calculating before and I think it was roughly if gas were $5/gallon, premium should cost about 8 cents or so more expensive to justify the better mileage. If it is 20 cents more, it is not worth the cost.


While I agree with your reasoning, I don't understand where you get the 1.6% improvement with 93 over 87 (8 cents divided by $5.00). Have you run a comparison of 93 & 87 over multiple tankfuls under similar conditions?

BMW has quoted a figure of 8% as the reduction in power for the R1200 motorcycle engine (12:1 compression) when using 87 octane vs. 93. And since I've seen no factual evidence as to the actual real world difference, I use that 8% as a guide. So with regular currently around $4.00 per gallon, I would choose premium at $4.32 or lower, but regular at $4.33.

Naturally, there's no proof that the performance of an air/oil cooled opposed twin is comparable to a BMW NA 3 liter 6 - or that the power difference equals the gas mileage difference, especially if one is not constantly stressing the motor. It would be helpful if EPA would include different octane results for their fuel economy figures on those cars which are tuned for 91, but will run on 87.

So like they say, I guess YMMV!

Tom


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## logicalscott (Jun 29, 2006)

I think it's pretty well documented that buying the 87 is a false or at least overstated economy as you get less miles per gallon....at a minimum you aren't getting near the savings it seems when you simply compare per gallon prices of 87 vs. 89 vs 91 or higher. What I think is a bit of a stretch is all the venom aimed at the OP suggesting that the lower octane somehow damages the engine for the future owner.

I'm a little turned off by the "screw the next owner" tone of his/her question, but how exactly does it harm the engine guys? 

On the other hand, just the way the question was asked makes me think the next thread will be about whether the effects of never changing the oil are likely to show up before 36,000 miles.

I just put the 89 in mine but I drive a ten year old E46 as a daily driver.


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## krsabs (Apr 22, 2011)

A car tuned for 91 or higher octane will absolutely get less mileage out of lower octane gas, so while you're saving several dollars on the fill, you are loosing money on the poorer mileage, and your fun factor is going down too. 

I experienced a relatively extreme example of this: a 1974 R60/6 beemer is spec'd to run 98 octane leaded fuel. When leaded fuel was being phased out, the highest level I could consistently find was 89 octane. However, I found I could go to a local municipal airport and fuel up with '100' octane aviation fuel. Using 89 octane, I recall getting 37 MPG, but while using avgas, I got 50+MPG, and that baby purred along like a Vacheron Constantin on wheels and was otherwise more responsive. That was 30 years ago, and I can't remember exact cost differences, but do recall that when I calculated the difference, it costs mere thousandths of a cent more per mile with avgas, then the regular unleaded.


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## Yorgi (Mar 17, 2005)

S93D said:


> Not true.
> 
> Power is subjective and a desire. How much it is worth is a personal decision.
> 
> Gas mileage is just dollars and cents. Premium gas will not result in sufficiently better gas mileage to pay for the increased cost. It will offset it slightly, though.....


Where do you get your info from?

Here is a excerpt from a Dinan white paper where they took a STOCK e46 M3 and dynoed it on 91 and 93 octane gas. There was a *11 hp difference or 4% with just a 2 point octane increase.*

_the stock M3 produced 280 hp (Figure 22- violet line). We then replaced the 91-octane fuel with 93 (available in most parts of the country). The M3's computer was so quick to determine that the fuel had been improved that it only took four dyno runs for the timing to adapt to the increased octane and raise the power up to 291 hp (Figure 22 - light blue and yellow lines). A gain of 11 hp with just 2 points of octane.
_

I have tested this myself and found I basically broke even with the extra mileage I got vs the price increase using 91 vs 87 in my 330Ci winter beater.

Based on TomK's post and Dinan's white paper it looks like you are losing about 8% of your power by switching to 87. It's significant.


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## BeemerMikeTX (Jun 6, 2010)

This thread is an interesting read, not the least of which is all the things that people know that are wrong. I hope everyone understands that octane rating and energy content/density of a gasoline or a gasoline component are separate, independent properties. For example, ethanol has a relatively high octane rating, but a relatively low energy content, so assuming your car's engine and fuel system are compatible with E85, your engine won't knock (or have the computer retard the timing) running E85, but your car won't go as far on a gallon of E85 as it would on a gallon of regular gasoline.

My comment earlier about the OP reminding me why I don't buy lease cars was NOT that I think running regular gas would necessarily damage the engine, but rather it is an indication of how lessees probably treat "their" cars in all ways related to upkeep, maintenance, and care.


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## Tom K. (May 10, 2008)

BeemerMikeTX said:


> This thread is an interesting read, not the least of which is all the things that people know that are wrong. I hope everyone understands that octane rating and energy content/density of a gasoline or a gasoline component are separate, independent properties.


I figured everyone contributing to this thread is aware that any power/mileage reduction with lower octane gas is due to the knock sensor causing the timing to be retarded.

The real issue is how often the timing change occurs, under what conditions, and whether it makes economic sense to use 87 octane (for NA motors) if the price is right.

Tom


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## Youngproexec (Mar 18, 2011)

Guy , you live New Jersey so why would this even be an issue. The price of premium there in NJ isn't even the price of regular gas elsewhere like in NY. Dont ruin the car for the next buyer/leaser..


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## krsabs (Apr 22, 2011)

I run premium in everything including my lawn mower, but pray tell, what is the factual basis for the conclusion that if one uses regular one will 'ruin the car'?


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## Yorgi (Mar 17, 2005)

krsabs said:


> I run premium in everything including my lawn mower, but pray tell, what is the factual basis for the conclusion that if one uses regular one will 'ruin the car'?


It's called pre-ignition or "pinging" or "knocking".

If an engine is designed to work with premium fuel and has a high compression ratio (like all BMW engines), when you run regular gas it can pre-ignite before the spark-plug fires due to compression alone (similar to how a diesel motor works). When you ignite fuel in the combustion chamber while the piston is still on an upward stroke it is very hard on the motor.

Contrary to common belief, high octane fuel is actually less volatile and more difficult to ignite than low octane gas. This is why high octane fuel will not pre-ignite when put under high pressure.

Modern ignition systems can retard timing to prevent pre-ignition but they can only go so far. If you run regular grade fuel and put a heavy load on the car in very hot conditions you will probably experience some pre-ignition. A common way to cause pre-ignition is to lug the car. (running the car at very low RPM due to using a gear too high for conditions) Also a carbed up engine will ping and the pinging will be worse if you are using regular grade fuel.


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## Tom K. (May 10, 2008)

Yorgi said:


> It's called pre-ignition or "pinging" or "knocking".
> 
> Modern ignition systems can retard timing to prevent pre-ignition but they can only go so far. If you run regular grade fuel and put a heavy load on the car in very hot conditions you will probably experience some pre-ignition.


I'm wondering about the basis for your "only go so far" statement. If the knock sensor is functioning properly, why wouldn't the engine shut down (or at least go into limp mode) to prevent damage, if retarding the ignition didn't eliminate the knocking almost immediately?

Although I've never experienced any pre-ignition on a modern car, my BMW motorcycle will occaisionally ping when lugging. Within 3 seconds, the ECU retards the timing and the motor smooths out again, albeit at a lower power output.

Tom


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## Yorgi (Mar 17, 2005)

Tom K. said:


> I'm wondering about the basis for your "only go so far" statement. If the knock sensor is functioning properly, why wouldn't the engine shut down (or at least go into limp mode) to prevent damage, if retarding the ignition didn't eliminate the knocking almost immediately?
> 
> Although I've never experienced any pre-ignition on a modern car, my BMW motorcycle will occaisionally ping when lugging. Within 3 seconds, the ECU retards the timing and the motor smooths out again, albeit at a lower power output.
> 
> Tom


There are many causes of pre-ignition and changing timing will not always help. A few examples:
1) hot spot in the engine due to carbon build up (carbon glows red hot and acts like a spark plug) 
2) a bad injector causing pre-ignition in one cylinder while the others are running normally
etc...

The knock sensor works great for things like lugging but you are still less likely to ever get knocking due to lugging if using a high octane fuel.


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## S93D (Apr 24, 2008)

Yorgi said:


> Where do you get your info from?
> 
> Here is a excerpt from a Dinan white paper where they took a STOCK e46 M3 and dynoed it on 91 and 93 octane gas. There was a *11 hp difference or 4% with just a 2 point octane increase.*
> 
> ...


Dinan's data may not be applicable to everyone since Dinan's goal is to maximize performance. The regular BMW tuning may not result in these figures.

The US EPA did a test and found a 1 mpg improvement in highway mileage or about 3%. Sorry about my 1.6% estimate. It was based on mid-grade vs. premium.

Anyway, I am not opposed to premium use. I use it. I just don't think one can fully justify it in terms of improved gas mileage. I would also like to see BMW data on the optimal octane for performance. I wonder if it is around 94?


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