I have a few Hemi's, one literally rattles like a diesel when it's cold and it doesn't go away completely when warm, one ticks when it's cold and comes off fast idle but the tick goes away if you goose the throttle a couple times, if you let it idle it will come back, completely goes away when warm. The third sounds fine.
I have tried a few synthetics. M1 makes them noisier than Valvoline Synthetic and Napa Synthetic and QSUD. Rislone, Lucas Synthetic, STP synthetic, Marvel Mystery Oil and Hyperlube additives make no difference at all. Running 5-30, 10-30, 10-40 no difference either.
The only oil I found that makes them quieter is Havoline DS Synthetic 5-20. And it is very noticeable. Any ideas why?