Ok went on a 1000 mile each way trip. Towing roughly 3k plus enclosed trailer with my bike in it. My deltas were between 7-14 depending on temp. When cool out...under 60 degrees the spread was on larger side. When above 60 degrees they were closer. At one point on I 81 in NC the grade was steep and long and spread went as far as 22 degrees it was about 65-70 degrees out, near top and as soon as I crested hill they dropped immediately to where they were before....within a couple minutes. Usually when empty my truck averages 6-10 degree difference. It's is a 2006 f350 Harley model with 65k. It's is a stock truck with just a 4inch turbo back...muffler only. What do we think about health of the truck. ECT was about 204 and eot was about 226. Top, I run Mobil.1 5/40 right now trying t-6 next time just to see.