Thanks for the info. The additives I was referring to were to compensate for the lead that has been removed from modern gasoline. I had a 71 caddy and ended up with a burnt valve in 91 because I didn't compensate for the missing lead. I will spend the addition for higher octane fuel because I feel that the engine will cleaner in the long run, and since I don't use my cars as daily drivers it isn't that much extra.