I just got back from a trip and my transmission temps were way higher than I'd like, peaking at over 240 on the climb into Summit County on I-70. I also hit these temps on the non-highway part of the drive doing 30 MPH on 6 from Golden to I-70 (only sharing for context if anyone is on CO). Clearly, it's time to upgrade the cooler. I see lots of installs with the Hayden 698, and some others with Hayden units that have a fan built in too. Tru-Cool and Derale also seem to be popular options.

Most of my towing requires me to head over steep grades and passes, and to manage hot summers in the Front Range and cold winters. Given all these factors, can anyone weigh in on what might be the best option for me? I'm not too worried about costs, but want the best option that will manage the high temps and not be an issue when the temperatures drop on the winter. I also do this drive regularly in the winter to hit the mountain, but I'm not towing anything.

I used a Tru-Cool on a Honda van I used to have. What I liked about it is it would only cool when the oil was hot enough, otherwise it bypassed the cooling fins. I thought that was a useful thing for the cold winters here. I never had an issue with it for the many years I had that van.

Also consider your driving style. I have a v6 and tow and take it super easy over mountain passes with my camper. I added a generic cooler from autozone mid trip one summer for safe measure, but I'll also camp behind semi trucks going up steep grades at 25 mph

I sell the Hayden cooler kits with bolt on bracket over at Iconic Fabrication Offroad. I'd recommend the 698 since it has the built in bypass for cold weather.