Bypass radiator/tranny cooler combo?

Just tossing my 2 cents in here, but a lot of things are going to a water to air whatever-you're-cooling interface. For example, the Corvette ZR1 and Camaro ZL1 both use water to air intercoolers for their supercharger systems. The Jaguar F-type and Landrover supercharged motors also use water to air systems. Heck, even Ford uses a water to air intercooler for their diesel. Reason they do this is that it's easier to maintain a consistent temperature. So for air, lube oil of whatever sort, it's easier to design a system when you have more consistency of the fluid you're working with (air, lube, water, etc...). Modern transmissions operate much better when the transmission fluid is up to operating temperature. Many modern transmissions have "Heating" strategies where they hold RPM's and drive with an unlocked torque converter more often when cold than when hot. By GM routing the transmission line as they have, they're trying to keep the transmission fluid at a sweet spot. Usually somewhere between 160 and 180 degrees. If the transmission fluid is cooler, it's warmed up. If the transmission fluid is hotter, then it's cooled down. That's typically what the OEM's are aiming for.

Just about all modern automatic transmissions tend to run an ATF cooler on one side of the radiator.