Auto trans cold weather operation...for us in the great white north

Taz107 · December 22, 2012

I have a 5.3 oil burning gasser, and seeing I do all my driving on the highway, I decided to try blocking off part off the rad with a old for-sale sign cut in two. Took off the plastic shroud over the rads, and dropped it in in two pieces, so there is still a small amount of airflow around each edge, and and some in the middle. Drove two hours on the highway tonight at -15 and temp needle never quite went off the 100 (212F) degree mark on the temp gauge. Truck came up to running tempature faster, cab warmed up faster, and best of all, it appears fuel consumption dropped by a fair bit. Will continue to monitor before I say for sure.

My question is on the operation of the auto transmission in cold weather. I have the towing pkg, but I very rarely tow in the winter. Because the tranny cooler is in front of the rads and my for sale sign "winter front", I am wondering if I should try to block, or at least reduce the airflow through it?

I watched on the DIC and my tranny never came above 40 (104 F) on the highway, which is way below operating temp from what I have been able to find on here...

I assume the tranny has a constant flow through the cooler, no thermostat setup like the cooling system correct? So then would blocking the tranny cooler help raise the temp of the tranny into the operating temp range, or closer to it, and therefore increase the effeciency of it?

Thoughts? I know with some of the aftermarket cooler kits I've seen a shutoff valve for cold weather operation, would that would be another option perhaps, instead of blocking off the airflow?

DaveH71 · December 22, 2012

A transmission really doesn't have an operating temp like an engine does, they have more of an operating range. The cooler you can keep it the better. Heat kills transmissions and 104 F is fine, especially at -15 for ambient temp. Your tranny should be around 40-80 degrees above ambient temp for non tow driving. If it starts to hit 230 then you can start worrying, don't stress over lower temps.