Okay not to threadjack or anything but I was just wondering the same thing...now I drive alot and really can't afford the high price of premium evry fill up, I try and run some through every 3rd tank..now is this bad ? on the gas cap door it states 91-92 octane..is this for a mechanical purpose? should I "only" be running premi? I hope I am not killing my car with 87 octane...it still works out cheaper to run a full tank of 89 octane and run a bottle of octane boost than running straight premi..this is only temporary untill i get back on my feet after nasty divorce..but I do notice the car loves premi more..
Regardz,
Jeremy