Trans Temps While Towing

Towing my 3700 lb trailer over Monarch pass has had me concerned of excessive temps, after a lot of research on here I decided not to put a cooler on and roll with it as is like Toyota and the dealers all say is fine. My listed trans temps are for the pan, not converter. Several trips in 95 deg temps never put me higher than coolant temp around 195. Large hills would see short rises up to 220 and quickly recover. I always tow in S4 and in the mountains it would quickly start rising if dropped to S3, a few times I had to grab 2nd gear and I was surprised that the temp would level off stay at 215-220. Converter temps would flare at 240 and once at 250 but only for a couple minutes. Overall it did great and I think the fluid should be fine if changed every 30k because the higher temps were for short periods of time.

 

For comparison I have a 24 with 30k miles. Live in south Florida bumper to bumper traffic. I’ve seen pan temps at 190-195 and converter once or twice above 200.

I’ve done a drain and fill already, color was dark, but did not smelly burnt at all. Shifting was the same more or less afterwards. Temps maybe dropped 5 degrees or so.

that’s without pulling any weight. Completely stock.