You missed my irony.
I run my trans with an external cooler, the trans fluid does not run through my rad, no provision for it to do so.
It takes forever for the trans fluid to warm up let alone get hot.
I can run my Camaro for an hour to the coast at 90mph and the trans is still not hot enough to burn off contaminants in the fluid.
Even in traffic it does not heat up, keeping it out of overdrive for a while does get some heat in there.I´ve also got a thermostat to control the trans fluid, it fully opens at 180º.
The manufacturer runs the fluid through the rad to get the fluid hot, that burns off accumulating muck in the fluid.
Think about an engine running at 240º, do you think the water in that rad is cooling the trans fluid ?
An external radiator is usually added for towing to bring the temperatures back to some kind of equilibrium.