jroof said:I haven't strayed from the 93 octane but for some reason I doubt that a four cylinder engine (turbo or not) would suffer from not having it, short and long term. But since I've got a full service station near me that's only charging $1.67 for premium, I'll stick with it. Hell, I've got a roommate driving an '02 Explorer V8 who uses regular. He's got 30k miles and no knocking/pinging or any other ill effects...however I've told him a million times he should be using premium.