OK.
With the little heat wave we have heres what I'm seeing:
Outside air temps about 70
Oil temp towing running around 200
Last year without the air dam I didnt see 200 on the oil temp gauge until air temps were in the 90's iirc.
So, I did 2 things at the same time - installed air dam, and changed oil.
IDK if Rotella changed the syn 5w40 since my last oil change or not.
I towed a trailer from Goshen, In to home, keeping a close watch on the temps.
Took the air dam off in the driveway at home.
When I do the second half of the trip the air temps are supposed to be about the same as today, so should be a good test.
Maybe there is a good reason they didnt put the air dam on the 2500/3500 dmax. I havent noticed much if any temp changes when running the eway empty, but towing it is noticable