Amsoil is nothing more then a marketing gimmick, I've always used Mobil 1, although the reformulation pissed me the hell off. Redline is the only oil I'd trust anymore because they are the only ones who didn't take the ZDDP out. If you don't know what it is the best way to explain it is that it is the anti-wear additive that was added to oil. The federal government made all street oil companies remove it as it reduces the life and efficiency of catalytic converters, however it reduces your engine life to not have it. Redline is billed as race oil so they still add the ZDDP.