Premium Gas

[rlsjr]

How often does everyone use premium gas? Is it 100% of the time, or do you use the low or mid-grade gas at times? And if you don't use premium 100% of the time, what kind of problems have you been seeing?

[mrbmwx5]

u must use premium all time.

[X5only]

manual and gas cap sticker says to use min. premium only (mine is 4.4) !

[4.6is Ryder]

Originally Posted by mrbmwx5

u must use premium all time.

Not always true...read your manual. When I took delivery I was told to use the mid-grade gas. After I got home I read the manual and sure enough it states that there is no real added benifit to using the high grade gas. The EMS system will burn it, but the system tends to work harder while looking for the optimum burn. I've had no problem in the 650i or the Cooper S....and I switched to mid-grade on the Cooper after getting this info.....Phil

[4.6is Ryder]

You must check the octane rating in your area...not all premiums are rated the same. I discovered this when I was visiting northern Texas.....Phil

[JCL]

Originally Posted by rlsjr

How often does everyone use premium gas? Is it 100% of the time, or do you use the low or mid-grade gas at times? And if you don't use premium 100% of the time, what kind of problems have you been seeing?

Premium? Never on the 325, sometimes on the X5 3.0, always on the 535 with the twin turbos. No problems whatsoever. You need good quality fuel, clean, with sufficient detergents. If your local fuel has marginal AKI rating, or fewer cleaning detergents in the mid-grade gas, you will likely benefit from premium. Only way to know is to try 89, it won't hurt your engine. If you notice any less power, or higher fuel consumption, go back to the premium. If not, enjoy the admittedly miniscule savings and run on mid grade. You can try regular, but I did notice a difference on 87, with less power. I stayed on 89 most of the time.

[Bimmer360]

my manual says on p.30 is min premium gasoline.

[SilverBullet]

I have an off topic question. Would using 89 make a difference if I have a Dinan chip? Is it best to stay with premium? I usually use premium, but I am considering changing to 89.

[JCL]

Originally Posted by Bimmer360

my manual says on p.30 is min premium gasoline.

Fuel quality has been improving over the past few years. BMW used to specifically require premium in owner's manuals, likely in part as a way to get a better quality fuel with more cleaning detergents. The variability in fuel across the US meant that they needed to specify premium to cover all the crap fuel being sold.

In the 2008 owner's manual, premium fuel is no longer 'required' but it is highly recommended. The manual notes that you can use any fuel down to 87 AKI, and talks about fuel quality, but does not make any mention of reduced performance.

I maintain that if you notice a difference in performance using the fuel available in your area, you should use premium. However, if your vehicle runs fine on 89 (as mine did) then you don't have to turn in your Roundels any longer.

[JCL]

Originally Posted by driverX5

I have an off topic question. Would using 89 make a difference if I have a Dinan chip? Is it best to stay with premium? I usually use premium, but I am considering changing to 89.

Depends what the chip does. What does Dinan say? If they are pushing the ignition timing, or changing the fuel mixture, you will likely see a performance degradation on 89. If they aren't changing timing (or fuel delivery) then I am not sure what they are selling, other than points towards a Dinan badge.