The point about using thinner oil when temps are below freezing is valid but I've never done it myself and never had any issues at sub freezing temps.

Try 15w40 or even 20w50 if you haven't and see how your engine runs. Especially before full operating temps are attained.

Personally I would not put 5w anything in my truck. Lost an oil pump and cam shaft in 38k miles running 5w30 because that's what the dealer put in it while it was still under warranty.

 

If it's not the oil pump cover being scored. My money would be on walked cam bearing. Tore mine apart to check oil pump do to occasionally oil light at hot idle. Minor scoring on pump but also found cam bearing almost all the way out. My readings are hot 8psi idle 30 psi 2000 rpm.

 

I looked at the cam bearings with a borescope and they all look good. From my limited knowledge anyway. Nothing obviously out of place.

 

Derp!! Yes, typo. It's 15W40. That's all I ever use. Thanks for catching that.

 

It would be obvious like this:

 

Definitely didn't see anything like that. Thankfully.