What oil for 2003 5.3 Vortec?

[arh]

+1 for the carbon build up on top of the piston. The GM Top Engine Cleaner works great. My 02 has had Valv Syn or NAPA Syn since day one and never uses a drop. I tried Quaker State HP a couple of changes ago and it seemed to REALLY quiet down the slap, almost to the point of not even there.

 

[pickled]

Amsoil SSO 0W30 and the Chevy 5.3 V8 are a very good combo. I posted a UOA previously from a workhorse type truck in the analysis section that ran SSO for an extended drain without any issue. M1 is definitely ok with these V8's as well. The 5.3's that I've seen for cam swaps/performance builds running M1 and/or Amsoil for a good chunk of their history were virtually spotless under the valve covers. Those two oils can keep a motor clean as [censored].