I'm going with rotella, 3 friends of mine use it and one of them has over 100,000 miles, it is safe for your trans, these idiots on this forum think they know everything!
Mine does it for a sec at 3000 rpm then again from 4000-4500. Get an aftermarket exhaust and you'll never hear it again! As for the valves hitting the engine that's bs, if that happened you couldnt say rebuild fast enough.