My Friend has a 2004 Chevy Avalanche with the 5.3 that he bought with good service records which has 150,000 miles and was needing advice on Conventional Motor Oil, which he is set on using. He isn't interested in Synthetic oils at all but was wondering what some of the best Conventional Oils would be considering he is going to be buying it in the big drum for all his vehicles which require 5w30. He was also wondering what a good OCI would be considering he has mixed driving of city/highway with some dirt roads on occasion. He isn't stuck on the 3,000 mile OCI either. Any thoughts or recomendations because I use PP and recomended GTX to Him. Any recomendations are welcome within reason.