So I'm reading my French owner's manual and it tells me I need to use unleaded fuel with an octane rating of AKI 91 or more, which in general is equivalent to NOR 95 or more. And, that the minimum octane required is AKI 87 (NOR 91). Does anyone know what AKI and NOR stand for? Are they possibly French acronyms? BTW, my English language "Quick Tips" only says to use uleaded fuel with a minimum of 87 octane.

Can someone tell me what I gain by using the the 91 octane fuel? How important is it to use the higher octane fuel? Is the minimum octane only for those cases when I can't get higher octane fuel?

Thanks in advance.

91 octan wast your money.... make you better when you spend more on gas... and you think the car run fast and better but it's not........


I used 87 octan on all my car... never have any problem..... I use it on my 850 turbo.... I also run it on my Lotus esprit turbo.. never have any problem over the year.... perfomance no change... save $$$$$$$$$$$$$$$$$$$$$$$$


you only use 91 octan when your car are pinging knocking noise.... when you go up hill than use 91 if not stick with 87

I have a 1997 850 R. For the last 6 months I have carefully monitored my mileage, g-tech performance, and which gas I use. This applies to the high pressure turbo engines only. I cannot speak for the non-turbo or low pressure turbo engines.

With 89 octane my 0-60mph time averages 6.98 seconds and my mileage averages 20.2mpg

With 91 octane my 0-60mph time averages 6.75 seconds and my mileage averages 22.3 mpg.

IF you can do the math then you will quickly realize that the extra power brings extra mileage, and the additional 2mpg actually saves me more than the extra 10 cents per gallon it costs to put in the mid grade.

330 miles with 89 (20.2mpg) takes 16.337 gallons at $1.50 = $24.51
330 miles with 91 (22.3mpg) takes 14.798 gallons at $1.60 = $23.68


I HAVE NEVER PUT IN 87 OCTANE FUEL IN MY CAR....so I cannot speak to the mileage and performance of 87 octane.

IT is true that these cars will run on 87 octane. It's also true that our bodies will run on nothing but Hamburgers, Fries, Twinkies and Coke. That doesn't mean it's the best diet. Just because you can doesn't mean you should.

SO TELL US MRSHA.....what tests have you done to prove to yourself that what you say is true. Have you run 5 tanks through and recorded your mileage? Or are you just barfing up what someone else told you.
--
Nathan Valles, Black 855R, Tint

Valles,
What's with the antagonism? Low self-esteem...Short man syndrome? This is a site to share advice/opinion not a flaming site. Leave your smart-ass replies at www.bimmer.org they LOVE to flame each other.

Good job! I have always wanted to see a comparison like that.

AKI (Anti Knock Index) is used in the US and Canada. It's a combined octane rating between a research/laboratory octane rating and a tested octane rating. Usually ranges between 87 and 93.

NOR is the french abbreviation for RON and is only the 'Research Octane Number' and is used in Europe and many other countries. Here the octane rating goes from 91 to 98 (and up to 102 in Japan AFAIK).

87 AKI octane in the US/Canada is about equivalent to 91 RON octane in Europe and is usually the minimum these cars need to function.

The base requirement (or at least what they were designed for) for most european cars is 95 RON, which roughly translates to about 91 AKI in the US/Canada.

Using low octane fuel should be OK as the engine management takes care of it, but the tradeoff is that it does lose power.

Bye, Arno.

Thanks for the great reply, Arno. That's exactly the kind of info I was looking for.

And thanks Nathan Valles for the idea of checking the mileage with the different types of fuel. I liked your "Hamburgers, Fries, Twinkies and Coke" analogy. Most of the gas stations around here have premium and regular, while the Esso station also has a middle grade. I'll have to check the numbers that go with the various names.

The computer retards the timing to compensate for the lower octane fuel . Lower octane will work. You may not notice a difference. If the manuel says to use 91, I would suggest doing so. It is in the book for a reason--to make the car run at peak performance.