joining a friend to tow a camper to Montrose, PA, 1300 mile trip. camper is a bumper pull, 7600 pounds. Were bound to encounter some hilly terrain, truck is a 2011 2500 Chevy ECLB with the 6.0. The truck will most likely get [censored] mileage, along with excess heat from the load. I normally run Pennzoil Conventional 5w30 in it, but for the trip would it be better to switch to Rotella T 10W30, T5 10W30, or Mobil 1 0W40? Or is there something better?