"Now I am lost, you mentioned in the post above, a 300 mile trip pulling the 14,000# trailer, just a large TT?"
Continental Cargo race trailer with bath package, tagged as an RV. 3100 lbs car, 400lb generator, two quads and misc support equipment, tools, fuel, etc.
"Did you have to wait 1000 miles before any towing? My truck (Ram diesel) had a break in period then an oil change and I was good to go.
I would think a high rpm gas engine would need a break in but I could be wrong"
I had about 600 on it, close enough.
In the way back, we bought a 2004 F-150 5.4L. Picked it up on a Wednesday with a still tacky Rhino Liner bed spray. New morning we hooked 6000lbs of car trailer and race car to the tail, loaded fuel jugs, food, equipment, etc and took off for San Antonio Raceway, about 240 miles distant. Truck had 30ish miles on it. We traded it October 20 for the wife's new F-150 at 160K. No issues. Only engine related repair was having to replace one coil pack around 130K. Oil changes were at 4K~6K intervals and after 100K I switched to 10w30 vs the 5w-20 normal requirement. No issues with chain followers and such.
The F-150 had about 1500 on it before we pulled the Keystone to Albuquerque and back. I did have an oil change done after that. I'll be much more picky about a dual turbo motor oil change mostly because oil is the life blood of a turbo. And most of that 1000+ mile trip the turbos were running in the 7~10 PSI range, so it was working the pull.