Ive read reports where they have soaked parts such as o rings in gas/acetone mixtures without a problem. And the mixture of acetone added in relation to the amount of gasoline was ~200x larger than quantities you would actually put it your car. Is it true? eh, who knows..
acetone is a acid if u ever watch mythbusters they did relitivly the same thing, when they did the gas tank rusted in a day and so on. it's just a bad i dea u might be thingin of moth balls a diff forum, if u wanna boost octane get octane booster.