I tried putting this post in transmissions but kept being referred to 4 specific threads.
We all know of the dangers of an overheated transmission, I would like to know what if any problems might arise from overcooling?.
I run an aftermarket transmission cooler in my car as I often use it for 150+ mile trips towing my caravan, but it also is used for unladen journeys in our freezing British summers!. What temperature are transmissions designed to run at?, I wonder if fitting a bypass thermostat would be worthwhile.
Its an '87 Olds Delta 88 unmodified apart from the trans cooler btw.

What temp is the trans running at right now? The temp has to be at least 75*f to shift in to 4th. I would say you want to be in the 165*-180* range for normal operation.

Well put Dan. You are right on the money.

I'm not sure about where the temperature should be, but typically, I hear it runs at about 125° above ambient temperature. As long as you keep it around there, you should be fine.

That was actually the way that is was explained to me by my friend Pete Luban of ATSG.

But we have a temperature chart/poster that came with Hayden Transmission Coolers as a wall display and it says that 160-180 is normal operating temp.