# 545i and premium gas



## bmwmch (May 12, 2004)

i have a 545i and although says premium unleaded i use regular unleaded - not convinced makes that much difference - am i wrong - does it make any difference re miles per gallon , performance or help re wear and tear ?


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## Baldmtn (Apr 28, 2004)

*Gas*

While I am not sure about the difference either, I know it is a warranty issue, if you have something fuel related ie injectors, fuel pump etc.. they can make you pay. I talked to a mechanic in the family and he highly suggested I run the premium in the car -- I am not a mechanic so what he told me I don't remember exactly but I trust him.....


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## woodsmit (May 19, 2004)

"Rising gas prices are making you think twice about pumping premium into your car. But can you get by on the cheaper stuff?

Yes, if your manufacturer recommends regular. And many do.

"By and large you're wasting money if you're putting high-octane gasoline in a car that doesn't need it," says Matthew Hall, a mechanical engineering professor at the University of Texas at Austin.

But changing to an octane rating below the manufacturer's suggestion could harm your car, says Andrew Barron, professor of chemistry and materialscq science at Rice University.

(Don't know what you need? Go to your glove compartment, dig all the way to the bottom and look in the manual. Or call a dealer.)

The octane level reflects how much the gasoline can resist engine "knock," a knocking or pinging sound that occurs from premature, uncontrolled combustion, says Jim Williams, senior manager at the American Petroleum Institute, an oil and natural gas trade association. Over time, engine knock can damage various engine parts such as the piston.

Also, if you use a lower grade on a car that requires higher, do you invalidate your warranty?

Toyota and Tommie Vaughn Ford say it won't, Honda says probably not, Nissan says it depends on various factors and cannot be answered in a general manner. "

http://www.chron.com/cs/CDA/ssistory.mpl/special/energycrisis/gasoline/2593995

Not specific to BMW but I think it still holds....


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## Nick325xiT 5spd (Dec 24, 2001)

Basically, anyone who runs a lower octane than their manufacturer recommends should have their car taken away. BMWs generally run better with HIGHER octane than is specified in the manual. NOT lower.


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## woodsmit (May 19, 2004)

"If your car requires high-octane gasoline and you habitually use regular gas because the engine exhibits no sign of knock, you're outsmarting yourself. Most modern, computer-controlled engines include a knock sensor that detects knock and retards the ignition timing, causing the spark plugs to fire slightly later in the cycle. This typically prevents abnormal combustion and knock, which allows vehicles specified for premium fuel to run on lower-grade gasoline if it is all that's available. While this removes the immediate hazard, it's a bad idea to make a habit of running a vehicle on gasoline of lower-than-recommended octane. Retarding the spark causes a richer fuel/air mixture, which decreases fuel economy, increases emissions, causes the engine to run hotter, and reduces the longevity of both the engine itself and the catalytic converter. The money you save by pumping low-grade fuel into a car that demands higher octane is lost anyway, in decreased fuel economy and possibly gradual damage. "

http://www.cars.com/carsapp/myrtleb...y&tf=/features/truthabout/gas/todaysgas1.tmpl
Additionaly.....


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## Nick325xiT 5spd (Dec 24, 2001)

Here's how much power you lose in a Jetta VR6 running 89 octane. 89, NOT 87 octane.


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## mrbelk (Dec 5, 2003)

That dyno is pretty telling.

Also, I would think that someone who spends ~60k on a car shouldn't really have a problem putting the good stuff in. The difference in a tank of premium vs. a tank of regular is only like $3.50. Certainly not enough to make a huge difference, even on an annual basis, especially considering that you are doing your car and the environment a disservice by running so rich.

-MrB


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## marinakorp (Oct 3, 2003)

Taken from the X5 board&#8230;

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"On the highway, I average about 18 mpg with 89 octane. With 93 octane, I average 21."

 <o></o>

My response

 <o></o>

"2 mpg on 18 gallons of fuel... is 36 miles less than you would have gone paying for super

there is about a .25 difference between regular and super

.25 * 18 = 4.50 savings for the tank fill up

assuming 2.10 is regular and 2.35 is super

1.714 gallons of regular (the 36 miles / 21 mpg) 3.60 in additional gas required to go the SAME distance as the Premium

4.50 - 3.60 = .90 in TOTAL savings by choosing regular over premium

WOW... Seems like you could same more by making cofee at home vs buying than getting regular vs premium"


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## sj3 (Feb 25, 2004)

Nick325xIT for president! I really liked the taking the car away part! That's hard core!

Sam


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## YeaYeaYea (Feb 11, 2004)

See the Powerchip discussion on octane vs. performance for the 545i

http://www.powerchipgroup.com/datasheets/2/Bmw0141.pdf

In summary, the car will adjust to lower octane fuel with no "obvious" problems, but I don't think one should regularly use lower octane fuels than what BMW specifies.

Lower octane fuels can contribute to carbon build-up that over time will affect engine performance.


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## hugh1850 (Jun 20, 2003)

I cannot possibly imagine why someone who would have the means to buy a 545i, has an issue with premium gas. There is what 10-15 cents in the difference between regular and supreme unleaded? That’s what $3 bucks more to fill up your car? :dunno: I'm sure that saving $3 per fill up will make you feel better when your engine throws you ace/duce for retarding the timing over and extended period of use. 

Sorry for being the A-hole


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## beewang (Dec 18, 2001)

bmwmch said:


> i have a 545i and although says premium unleaded i use regular unleaded - not convinced makes that much difference - am i wrong - does it make any difference re miles per gallon , performance or help re wear and tear ?


If you are concern with money, then you should've purchased a 525 instead of 545.

RTFM, BMWs runs on Premium gas (AT LEAST 91 ) The premium gas may not make a difference on Honda Accord or Ford Trucks, but it makes a huge difference on German luxury/Sports car.

Do some research and you will realize what an idiot you are  !

beewang


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## hugh1850 (Jun 20, 2003)

mrbelk said:


> That dyno is pretty telling.
> 
> Also, I would think that someone who spends ~60k on a car shouldn't really have a problem putting the good stuff in. The difference in a tank of premium vs. a tank of regular is only like $3.50. Certainly not enough to make a huge difference, even on an annual basis, especially considering that you are doing your car and the environment a disservice by running so rich.
> 
> -MrB


Didn't read your post... :stupid:


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## bmwmch (May 12, 2004)

thanks everyone - great info ! - never really understood the details or the why - somewhat of a reverse question - if i now switch back to premium , does the engine have the ability to "adjust back" re performance etc given the use of premium going forward - so far have not noticed any ill effects of using lower grade nor did i notice any difference when i did use the higher grade ... but explainations above convince me to stay with the premium grade .


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## marinakorp (Oct 3, 2003)

bmwmch said:


> thanks everyone - great info ! - never really understood the details or the why - somewhat of a reverse question - if i now switch back to premium , does the engine have the ability to "adjust back" re performance etc given the use of premium going forward - so far have not noticed any ill effects of using lower grade nor did i notice any difference when i did use the higher grade ... but explainations above convince me to stay with the premium grade .


should not be a problem


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## 3Aims (Mar 25, 2004)

Marina, I noticed you have the Powerchip software installed. Did I read your Dyno correctly? What gives?


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## dagoo98 (Apr 23, 2004)

bmwmch said:


> thanks everyone - great info ! - never really understood the details or the why - somewhat of a reverse question - if i now switch back to premium , does the engine have the ability to "adjust back" re performance etc given the use of premium going forward - so far have not noticed any ill effects of using lower grade nor did i notice any difference when i did use the higher grade ... but explainations above convince me to stay with the premium grade .


You haven't had the car for that long so you probably haven't had enough time with the car to really know what it feels like to feel the difference between premium and regular gasoline. Especially considering that unless you put a drive a lot everyday most of the time that you have driven the car so far has been during the break-in period.


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## LA525iT (Oct 27, 2003)

beewang said:


> If you are concern with money, then you should've purchased a 525 instead of 545.
> 
> RTFM, BMWs runs on Premium gas (AT LEAST 91 ) The premium gas may not make a difference on Honda Accord or Ford Trucks, but it makes a huge difference on German luxury/Sports car.
> 
> ...


Please dont bash the 525 owners. My 525 has had nothing less than 91 to drink during her pampered life.


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## MMMM_ERT (Mar 13, 2004)

I didn't spend big dolla on a performance car to turn around and put cheap
gas in it. We're talking what...10 cents a gallon difference... 18 gallon tank...$1.80
per fill up. Not worth using the cheaper stuff if you ask me... :dunno: 

...and like everyone else has pointed out. BMW recommends you run hi octane.
Wish we had better than 91 octane here in the Peoples Republic of California.


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## beewang (Dec 18, 2001)

MMMM_ERT said:


> ...Wish we had better than 91 octane here in the Peoples Republic of California.


Be careful of what you wish for :neener: 101 Octane Trick Racing gas Are you sure you want to buyit??!!  $4.50 a gallon 

In the hot summer months, i'd run a 50% Blend of 101 Octane trick gas :thumbup: It does wonders for the S62 V8s, it does hurt the wallet thou :eeps:

cheers,

beewang :bigpimp:


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## MMMM_ERT (Mar 13, 2004)

I knew about the race gas.... :thumbup:

I was more thinking along the lines of the 94 Octane Sunoco that the East Coast gets.. 
available on every street corner gas station. :supdude: Lucky Bastages... :slap:



beewang said:


> Be careful of what you wish for :neener: 101 Octane Trick Racing gas Are you sure you want to buyit??!!  $4.50 a gallon
> 
> In the hot summer months, i'd run a 50% Blend of 101 Octane trick gas :thumbup: It does wonders for the S62 V8s, it does hurt the wallet thou :eeps:
> 
> ...


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## Da'Vroom Vroom (Aug 15, 2004)

marinakorp said:


> Taken from the X5 board&#8230;
> 
> <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
> 
> ...


Nice wheels on that Touring Sedan...

I just came into possession of a 94' Touring Sedan and want to change the wheels...

What size are the wheels on the Silver BMW you use in your signature? Where did you get them?

Thanks for your time,

Juliene

[email protected]


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## redbeemer (Mar 12, 2005)

mrbelk said:


> I would think that someone who spends ~60k on a car shouldn't really have a problem putting the good stuff in.


the problm is you think the higher octane is somehow better than lower octane. that is falst. The higher the octane the worse the gasoline burnes. No way around that it is worse gas that is higher in octane rating (there is not octane in gasoline anyuway. It is just a measurement system). It simply resists pinging better because it burns worse. Higher octane has less energy per volume than lowre octane. You are simply paroting what the gasoline manufacturers want you to think because the real graph you should loook at is the profit margin for the various grades of gasoline. It would look like that vw curve too!

Ever since 1982 when I learned this gasoline information in organic chemistry I have been using the better 87 and 89 octane shunning the much worse 91 RON and my cars last forever. My current 525 is a 2002 with no ill effects after three years of driving on 87.


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## vern (Apr 19, 2002)

beewang said:


> If you are concern with money, then you should've purchased a 525 instead of 545.
> !
> 
> beewang


You shouldn't have bought any model BMW if you are concerned about not buying premium gas!!!
Cheers
vern


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## redbeemer (Mar 12, 2005)

I put the better burning higher btu lower octaine gasoline in my bimmer.
I dont put the worse burning lower btu higher octane gasoline in my bimmer.
Price is irrelevent. I can drive down the street to get a different price and the gasoline would be exactly the same. The only difference in the gasoline is the lower the octane rating the better the gasoline (look it up on the web if you dont understand chemistry). 

What part of putting the best gasoline in my bmw dont you understand?


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## redbeemer (Mar 12, 2005)

*If it make YOU feel better to waste your money on premium, knock yourself out*

BMW uses the term "Premium Unleaded Gasoline" with the knowledge that state laws
vary with regard to the octane that can be advertised as "premium". 89 probably
represents the lowest end of the range of fuel commonly advertised as premium in
the U.S., so any fuel labeled premium will meet the minimum specification. To
answer the original question, no, 89 octane won't hurt his car, and yes, he's
wasting money buying 92. The only time higher octane is of any benefit is if the
car pings on the recommended grade, the timing is advanced, compression is higher
than stock, or the car has forced induction. Pinging occurs when the spark
occurs too early in the cycle. If the fuel/air charge is not compressed enough
(i.e. harder to light) the charge explodes rather than burning at a controlled
rate. The two means of eliminating this condition are to a) use higher octane
fuel which is more resistant to ignition and burns slower and cooler (roughly 1
degree per point of octane) or b) retarding the ignition timing. This is exactly
what happens when the knock sensor detects pinging. In response, the computer
pulls out timing to prevent the pinging. What he means by "overkilling" is that
92 is overkill for his engine, i.e. more than is needed. It won't hurt it, but
it doesn't do any good either. If it makes you feel better to put premium in
your car, knock yourself out (yes, pun intended!)
For a good (and brief) explanation of how octane is measured, what AKI and RON
mean, and what it means to your engine, check this link:
http://www.exxon.com/exxon_productdata/lube_encyclopedia/octane_number.html

http://member.rivernet.com.au/btaylor/BMWText/technical/PingingAndHiOctane.html


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## slowdelsol (Mar 13, 2005)

89 is all i pump my 99 528 run fine to me..but i do wonder if it would be faster with 91..


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## FenPhen (Jan 13, 2004)

redbeemer said:


> What part of putting the best gasoline in my bmw dont you understand?


The part you don't understand is how that gasoline is used in your engine. Diesel has more energy per volume than gasoline, but I'd hope you wouldn't recommend that for your car.

You have a high-compression engine. A high-compression needs a gas that burns cleanly and doesn't explode under pressure.

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


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