Has BMW changed its fuel recommendations?

[first5ny]

Manual for my 1998 528 says use a fuel with a minimum 89 octane rating. In a response from BMW, they state that the recommended octane rating is 91. Have they changed there recommendation since my car was new?

 

[Big Daddy]

My manual (for my 750iL) lists two ratings, one is a method not labeled on the pumps here in the US and is 87. I am not sure what they called this method, maybe AKI? Then they list the method used here in the US, I think Research Method, and it is listed at 91. SO I need premium fuel as do you!

 

[first5ny]

I'll check my manual tonight, but I think it only has one recommendation for 89. The gas cap also says use minimum of 89. If this is the case is 89 ok? I've used 89 for the 1st couple of months I've had the car and it seemed ok. Only recently did I change to 93. Only difference I noticed was slight increase in MPG.

 

[Big Daddy]

If you manual states that 89 is acceptable using the index used in the US, then by all means us 89. Was the MPG increase enough to cover the cost difference between 89 and 93? Most likely not, then I would use the 89.

 

[Millreef]

Mine specifies 91...ouch...for a couple of days over the weekend that meant Cdn $1.00/litre...

 

[Big Daddy]

Mine too is 91. Yesterday at Costco $2.00 a gallon. I think that has come down a bit since last time.

 

[epj3]

Mine too is 91. Yesterday at Costco $2.00 a gallon. I think that has come down a bit since last time.

Wow and costco is supposed to be cheap... premium is around 1.82/gallon here right now. I use 89 though and the car runs just as good as 91. I believe 89 is the reccomended anyways... not sure though.

 

[first5ny]

Finally checked the manual and it says to use 89 AKI. What does 89 AKI mean in the states? 91?

 

[Big Daddy]

AKI = Anti Knock Index! It is just a different rating system. My manual says 89 AKI/91 RON

 

[first5ny]

Mymanual just says 89 AKI. The octane rating at the pumps is that AKI or Ron? If yours says 91 RON it sounds like thats what I need. Thanks.

 

[Big Daddy]

I chcked my manual and found that it reads: "Your BMW is designed to operate with un-leaded fuel with an Anti-Knock index of 87 AKI. This designation is comparable to Research Octane Number 91 RON."

Here in the US we use RON, therefore we need 91 Octane fuel!