It was only down 1/2 qt. I was getting ready to take off on a 1000 mile trip pulling a trailer and I just wanted to top off the oil in order for the engine to have plenty. What weight do most of you use? I was thinking of going to 15-40 at the first change.

15 W 40 is used a lot and so is 5 W 40. I am running 5 W 40 in my 6.0. 10 W 30 is for gas motors.
Dave
Times 2. 5 W 40 Rotella T6 full syn. in the dezel.. 10 W 30 Castrol in the Gasser. (think'n 'bout going full Syn. in that soon too.)