I've got a set of the Hughes lifters in my 408. They work just fine. Hughes recommends 10w30 oil for use with their roller lifters and that's what I'm running now. I am a big fan of castrol gtx 20/50, have ran it year round with no issues for decades in NW Washington and would like to use it again. Anyone using these lifters using any other weight oil than the recommended 10/30...your experience????