Our new 2018, 2500 CTD, 4x4 has 7200 miles now & 1st oil change. We're prepping for 1st trip South (1300 miles) with new truck, towing 15K Montana High Country in 2 weeks. The owners manual says to keep 1st 500 miles towing, @ no more than 50mph. That speed is almost hazardous going thru...