I run German Castroil 0w30(the stuff that use to be green), since I stock a lot of it for my car. It works great, very quiet motor and I go about 5 to 8k between oil changes. I ran a the stock 6 liter ac delco filter, PF61.

 

Thanks for the tips I also ran Ams Oil in my other truck I figured try Mobil 1 just for something diffrent hope it works out good I plan on changing the oil every 4000 miles.

 

I run the M1 and the ac delco pf61 which is the same filter as the pf 59 my truck came with, prefer it over the later pf46 for the extra capicty. Change my oil 2 times a year but I only drive about 100-120 miles a week. Nice to work 5 miles from the house!!

 

I thought that the 61 was different from the 59 in that it doesn't have the anti drain back valve and the 59 did, but I could be wrong? I used to use PF59's and Mobil1, but recently switched to Amsoil with a Mobil1 filter. I plan to start using Amsoil oil filters when I use the other Mobil1 filter that I have.