Which oil for 2003 Silverado 6.0L?

[CleanSump]

I was considering a ow for the winter cold starts. It starts up fine due to being fully winterized but is pretty chattery at first (seems like lifters) then quiets down. Was thinking ow might help prevent minor wear since it has better cold flow.

You can give it a try. It won't hurt anything. -40F is down there where 0W-30 might chatter less. I'd still use either HPL EC 30 or the Valvoline Restore & Protect to see if the lifter chatter goes away with some cleaning. HPL EC 30 eliminated my BMW startup lifter chatter in just 100 or 200 miles. It doesn't usually get below the teens here, though we do get occasional drops to single digits. Not Artic conditions like you have.