To be honest I still use Rotella oil. I have heard good things about several other brands. But being in this business I change my oil at 3500 mile intervals, and recommend this to my customers. I hardly every have documentation of what oil customers use when their cores arrive. But I can tell when someone has a good regular oil change interval. These are the injectors that have good/little wear with nearly 200k miles on them. I have also seen complete crap from a truck with 75k miles on them. For me it is more about keeping fresh oil/filters in the system.