I was talking to my local tranny shop about tranny temps when towing, noting that mine climbs to about 195-205 degrees when going up hill, and then leveling out about 186 during steady towing, and he told me that was acceptable. I then asked about synthetic oil in the tranny and would it help. He told me that he has not been sold on the synthetic oil as he has not seen enough evidence where it should be switched from dino oil. He also recommended a oil change yearly in the tranny if towing on a regular basis. I think that when I do take it in, I will most likely switch to Mobil syn oil in there. Any thoughts?