[Davidf]

This tread has me thinking: Did GM even offer the trans coolers as an option? If so, I imagine it was intended only for hot climate regions. I agree that cold trans fluid is not so great. Also, on modern cars that have trans oil coolers separate from the radiator (and even the ones that flow just through the radiator in some cases...BMW for example) the trans cooler is thermostatically controlled for faster warming of fluid and to prevent excess cooling. This way, it works properly in all climates. The danger of the thermostatically controlled through the radiator only coolers is that if the thermostat fails closed, you can cook the fluid and damage the transmission...