I'm the oddball here. I run Pentosin High Performance. More Zinc than the other oils for better camshaft protection.

 

is anyone here running a 5W40? I see a lot of 10w30 getting mentioned but I wouldn't think cold would be an issue, I'd want it thicker when hot

 

15w-40 here quieted things down a crap ton.

 

right on, I'm planning 5w40 on my next one, I deal with colder ambient temps at night, so I don't want to thick on cold starts

 

10w-40 here.

 

I just switched to amsoil signature series 5w30 and noticed the truck at cold start up would be at 60psi (like before) but when warm it would be at 40 psi at idle (like before) but while driving warm it's now 50 psi cruising. (Before would be about 60psi) only difference I've seen. But if I run it out to 6500 rpm it's just over 60psi

 

Im running rotella t for the added zinc protection. Runs well too...

 

Rotella t 15 40 here also

 

I run Mobil-1 10w-30 in my truck year round. There's really not a reason to differ to much from what is factory recommended unless you've got some significant internal engine mods. The tolerances and robustness of modern engines (especially the LS motors) mean much less wear in places you'd see in older engines. How many of you have opened up LS engines with 2-300k on the clock and still seen the cross hatching on the cylinder walls? No need to change oil weights unless you see severe temperatures in your climate. If you've got oil pressure or engine noise issues, putting thick oil in it isn't fixing what's broken.

Most problems I see come from running oil way too long (sludge) or an engine that burns large amounts of oil (sucked through PCV or some other source) which coats the intake manifold in oil, kills engine sensors, and causes sludge buildups.