Which brand of gas do you use?

[cambit]

Originally Posted by mkiv808

100 won't benefit your car at all, neither will "95". It doesn't have the compression/timing to utilize the extra octane.

What about 93 octane vs 91 octane?

[Ezio]

shell.

[Khrishna]

Originally Posted by mkiv808

100 won't benefit your car at all, neither will "95". It doesn't have the compression/timing to utilize the extra octane.

Say waaaat? 12.0:1 compression rate isnt high compression? and ECU head room for timing advance..yes DEFINITLY will benefit from higher octane, once ECU has had time to adapt to the increase

[jpan08]

Originally Posted by GrussGott

This what the ED BMW delivery people told me: 91 is what to buy, everything else does little or nothing unless you "re-engineer the car"

Interesting, maybe I should start cutting my 93 octane with 89 to save me a dollar a tank.

[KawBoy]

BP

[mkiv808]

Originally Posted by Khrishna

Say waaaat? 12.0:1 compression rate isnt high compression? and ECU head room for timing advance..yes DEFINITLY will benefit from higher octane, once ECU has had time to adapt to the increase

Go test it on a dyno and let's see what happens...

[kawasaki00]

Originally Posted by DBH

I thought Sunoco stopped making "260" a few years ago. To my knowledge there's none available at Sonoco stations in southeastern PA. If anybody knows of one, please post address.

It is being phased out this coming year. It is no longer being produced but there is enough quantity till next summer. After that all gone.

[TheDeliverator]

IIRC: There have been a few threads here on how the ECU adapts to blending higher octane gases. I seem to remember something about the ECU not adjusting much above 95 octane.

I could be wrong but I do believe the ECU will adjust between 91 and 93 octane.

[tl351698]

2nd post here, picking up my 1st e92 on the 29th! something to consider when choosing gas stations though: I've ridden street bikes for several years...I always filled up with premium gas at stations that have a dedicated fuel line/hose for each type of octane level (as opposed to one hose for all types). This is especially important in a motorcycle (3.5 or 4 gallon tank). If the person in front of you bought the low octane, there could be ~ a gallon of 85 or 87 octane in the hose that you would be pumping into your tank before the premium would start making it into your tank....now 1 gallon in a 16 gallon tank might not be much, but it could be the difference...

[GrussGott]

Originally Posted by TheDeliverator

IIRC: There have been a few threads here on how the ECU adapts to blending higher octane gases. I seem to remember something about the ECU not adjusting much above 95 octane.

I could be wrong but I do believe the ECU will adjust between 91 and 93 octane.

I ain't no expert but I'm guessing it will adjust for knock and emissions but that it means squat at the wheels for power.

Of course I really have no idea, but I would LOVE to see some dynos of 91 v 93

[Notsorich]

Its either Chevron or shell for me. If the shell by me isnt cheaper then the chevron id go to chevron over the shell, not becuase i think there is a significant difference but I think its more out of Habit and me being brain washed.

[Grail05]

CHEVRON since day 1... not once i use any other gas company... TECHRON

[kevblah]

Usually Shell V-Power 93.

[suprafrank]

either Chevron or Shell but mostly Shell unless no Shell around then Chevron. Some how I feel my cars including M3 are more responsive with Shell than Chevron. Unfortunately we only get 91 grade as premium in CA.

[kyle46]

Chevron works better for my car IMO..i used to fill up with shell V all the time. i let my butt dyno be the judge on this one, therefore i could be wrong.

[0_to_60]

shell 91

[empilot]

Octane provides one thing: resistance to knock. Knock is caused by pre-ignition of the fuel due to high compression which is bad for performance and the health of your engine. If you're putting low octane in your M3's engine to save a few bucks you're in the wrong car and you are damaging your engine and you may find repairs costing you more than the money you've saved on gas over time.

These cars cost $70k+ because they are designed by the world's top engineers with years of R&D put into their design. The world's lightest V8 costs a lot to design and maintain and you pay for it when you buy one. Why would you ignore the manufacturer's warning on octane?

If you're eating ramen noodles to afford high octane gas for your M3 it's time to trade-in for a Civic or something more conducive to saving money on gas.

[nchan50]

Shell

[apecush]

Originally Posted by empilot

If you're putting low octane in your M3's engine to save a few bucks you're in the wrong car and you are damaging your engine

No you're not. Individual cylinder knock sensing is there for a reason. The ECU just pulls timing, netting you less power and worse fuel economy. It does this for 91 fuel as well, just to a lesser extent versus 87.

The ecu pushes for a preset value of maximum advance (which would be achieved using 95+ octane fuel) until it senses knock, and then dials back a predetermined amount. This is where maximum power lives for the given fuel grade.

[S65NAPWR]

Originally Posted by TheDeliverator

IIRC: There have been a few threads here on how the ECU adapts to blending higher octane gases. I seem to remember something about the ECU not adjusting much above 95 octane.

I could be wrong but I do believe the ECU will adjust between 91 and 93 octane.

This is correct, see above.

[Pontrelli]

Only Shell

[empilot]

Originally Posted by apecush

No you're not. Individual cylinder knock sensing is there for a reason. The ECU just pulls timing, netting you less power and worse fuel economy. It does this for 91 fuel as well, just to a lesser extent versus 87.

The ecu pushes for a preset value of maximum advance (which would be achieved using 95+ octane fuel) until it senses knock, and then dials back a predetermined amount. This is where maximum power lives for the given fuel grade.

Why not 85 then? Why does BMW even make a recommendation?

You're absolutely right about the ECU and like you said it has to sense knock before it adjusts cylinder timing and using lower than recommended octane will provide it plenty of knock to prevent.

Using 87 or 89 in a pinch won't hurt anything and that is what the ECU adjustment is for. It also adjusts for changes in oxygen levels due to altitude. Ever notice that 85 octane is usually only found at higher elevations and 91 is the highest octane you can get at those same stations? Thinner air means lower compression, so you can get away with a lower octane.

Consistent use of other than the recommended fuel will damage your engine and you risk voiding your warranty.

I'm just trying to point out that going against the manufacturer's advice is not good for your wallet or your engine. Don't have to take my word for it, though...

Straight from BMW: "Do not use any gasoline below the specified minimum fuel grade. Otherwise the engine could be damaged." BMW recommends 93 octane with a minimum fuel grade of 91.

Take that money you're saving on lower octane and have your ECU re-mapped for 87. Sure it will void your warranty but you're doing that anyway.