Thank you for that info... I've always experienced that lugging the engine resultsJust some thoughts I had:
I've owned a few 40K to 50K # motorhomes with 11L & 12.7L diesel engines and Allison 6 speed autos. The rule to keep them from getting hot is "keep the rpm up. Don't lug em." I don't know if the same applies to gasoline engines.
For many yrs I've been doing used ATF analysis with some of my vehicles. My ATF samples I send to JG Lubricant Services because a President/owner, x GM fluid engineer Tom Johnson, is at ph 877-971-7799 ext#2 to answer question(s). I've talked to him several times. Give him a call. Nice man.
IIRC, Tom says your Dexron6 atf tempsaren't hurting a thing. Prolonged temp greater than 235 and the fluid starts to degrade.
If your worried about Dexron6 viscosity thinning out, you might consider running an Allison approved TES668 atf. They have a higher viscosity. Some Corvette folks that "track" their car do it.
You might consider ordering some kits too so you can see what is what.
https://www.jglubricantservices.com/docs/Technical Information Sheet.pdf
https://www.allisontransmission.com/parts-service/approved-fluids/on-highway-fluids
in less mpg and more wear/ heat as well with gas engines. I used to tow this rig
with my 1994 C1500 ext cab.. It has more power than my 6.2 and a 4L80e trans.
Lugging it in 4th OD and rpm'ing it in 3rd gear. But using 3rd 1:1 on any incline
was the only way to go.
I'm using Liqui Moly ATF 1800 in my 6l80e. It's supposed to be a little bit
of an upgrade to Dex VI. So I'm not quite concerned about overheating the trans
fluid.. yet
Just found this whole situation odd that this situation exists at all