I've had two of the 360/300hp magnum crate engines and they were quiet other than the occasional noisey lifter at startup after sitting a few days. Sometimes one or more would linger for a few miles or more and then finally quiet down. Did this engine sit for awhile? Maybe it will eventually quiet down after it comes some miles on it and an oil change. I always ran Valvoline 10W-30 conventional here in Florida, FWIW. Wish I still had one of those engines. Ya, I think assembly might have been a little shoddy with some seeping gaskets, but geez, what a torquey engine with instant throttle response! I think the 300hp and 375lb/ft torque was underrated!