Since the summer has hit, my car has been pulling timing a lot, and it's been driving me nuts! Anyways last week I was in AZ and I put some 92 Octane in my car (In Vegas 91 is the best you can get, besides race fuel), and it seemed to pull much smoother. So yesterday when I filled up I put 1 gallon of 100 Octane race gas and filled up the rest with 91 (both from 76') and after about 50 miles my car feels much better. I am guessing I am probably around 92 ~ 93 Octane with this mix. I forgot my old algebra skills and can't remember how to figure out exactly where I'm at now. Does anyone know the formula to figure this out? Anyone else out there doing this? or have a special mix you use? Can this hurt anything? I try to stay away from Octane boosters, I just don't feel safe using them. The race gas was about 4.20 per gallon, it seemed well worth the extra 2 bucks when filling up...