I have a stock 1981 U.S. spec 924 I just acquired. Please don't blast me for this question (or hell, go ahead if you just can't help yourself). I have a factory manual that says 91 octane (RON, which I believe is the European standard) or 87 on the US standard. An old contemporary Road & Track test I have says 91 octane. I have poked around here and 924.org and not found an answer.

Around here (midwest usa) 91 - 93 octane is premium and 87 is regular. I have no problem burning premium if that is what it needs, but don't want to pay the extra for it if there is no benefit.

 

87 should be fine.
they have pretty low compression.

 

Thanks! 9.0 to 1, a little higher than the earlier ones, but not too high.

 

different engines, but the US spec 944 with 9.5:1 still calls for 87 octane.

 

I know the 944S calls for 90 with 10.9:1 compression, so 87 is more than likely fine for the 924.

 

I ran 87 with my 80 924 had no issues and ran like a top.

 

It will perform a bit better with the gas it says it needs...it wont die with lower octane but may make some strange clicking noises when accelerating and ofcourse offer a bit less power.