What temps were you seeing? You have to watch a trans running to cold also. Big isn't always better. In cold weather it still needs to run normal driving in the 140/150 range at minimum.

 

Bigger tranny cooler will help a some, but the best thing you can do to keep tranny temps down is to increase the fluid capacity. Look into a larger/deeper pan like a Mag-Hytech or PML.

Simply going to a larger cooler can have adverse effects when not towing in colder climates. If the transmission fluid doesn't reach at least 140* at the pan, transmission damage can result. Having more fluid guards against over-heating while not increasing the chance of running under temp...

 

running the trans fluid too cold is probably not an issue with the stock cooler in the loop. Flow through the trans cooler is controlled with a thermostat inside the cooler itself. I haven't found what the temp setting is but here is what the manual says.

TRANSMISSION OIL COOLER THERMOSTAT

NOTE: The transmission oil cooler uses an internal thermostat to control transmission oil flow through the cooler. This thermostat is servicable. 1. Remove the transmission oil cooler (Refer to 07 - Cooling/Transmission/COOLER, Transmission Oil - Removal) . 2. Remove the snap ring (4) retaining the thermostat end plug (3). 3. Remove the end plug (3), thermostat (5) and spring (2) from transmission oil cooler .

 

What temps were you seeing ? Actually running it through the radiator cooler kinda defeats the purpose. The factory coolers are what stop up and cause a great deal of trans failures. You can run a add on cooler that way. But the few I've run I took the radiator cooler out of the loop. So do most trans shops when they install a add on. I'm curious to what degree it lowers temps that way.

 

Im pulling a 26' camper, its nothing that big or heavy. Also i did have a bad torque converter that entire time i was towing which is probalby 85% due to my tranny overheating. My truck is set in metric and if i remember right i saw the temperature come up to 190 Celcius. It was right up there on the gauge. But i know the bigger rad will help and i'm doing it more for prevention, better be safe than sorry. I also need to change my gears as its just not enough, especially when it's windy.

 

+1 on the larger pan. if a truck already has an oil cooler, going to a larger one will help a little bit, but nothing helps as much as going to a larger pan that increases capacity. most also have cooling fins that are heat sinks and make a big difference.

lot of the big farm owners who bought from the dealership where i worked tow heavy and almost all of them have the stock cooler but larger pans.