I have a 4L80E manual behind a Chev Diesel in my 6x6 camper. It runs at 120 to 130 C on the road climbing higher on hills. I have been told I should run Castrol Transmax Z synthetic instead of the Dexron I have in it now.
To change oils is there a cheaper flush oil to put through instead of just running the synthetic through untill the colour changes.
The mob I bought it from said that as it is a manual auto it does not have a lockup TC therefore runs hotter. I have two coolers and the temp after the coolers is a fairly steady 60 to 80 C.
Didiman