I got a 04 6.0. I have been using regular Rotella T oil 15w40, and it may stumble a little on cold starts. But I tried some rotella T4 15w40 for this last oil change and it started skipping bad shaking the truck on every cold start after the oil change.
BUT, I tried some archoil, and it seemed to clear up COMPLETELY. Not so much as a stumble now.
What does this mean??? What kind of underlying issues could I be having? I'm going to continue to use the archoil, because it seems like it's going to prolong the life of my injectors and high pressure oil system.