I have been using a 93 octane( BP/Amoco) gasoline for my 1993 535i since I got the car almost a month ago. I just read from the Roadfly E34 forum this posting regarding the 535i:


However, I'm happy to trade some power for a car that runs on 87 octane (that's what it REQUIRES -- higher octane will reduce its performance and even harm the engine long-term), and is simple and straightforward to work on.
Is this for real? or just another IMO/2 cents worth baseless opinion. If so I must be foolish to pay more money on the pump for no return and might even harm the car's engine in the long run.