So I'm sitting at the plant waiting to unload and I'm rummaging through the glove box and find the engine operators manual. So being an oil nerd I find the oil section. Not too different than a cars. Can run on a few lubes!
We have two shops service our fleet. One uses Rotella 15w40. The shop that services my truck uses Valvoline Premium Blue 15w40. But at the garage we have Mobil Fleet 15w40.