If you want to, you can bypass the radiator. I did it in my old car because it wasn't a daily driver and I had put an aftermarket radiator in anyways without the cooler built in. But for the FX, I ran it through the radiator because otherwise, it will take a long time for the transmission fluid to hit normal operating temperature in colder weather. If it doesn't, it's not going to shift well and the operation will be iffy. The radiator cooler keeps the fluid at a good operating temperature, the auxiliary cooler is just there to keep it from overheating. At least that's what I hope. I have heard about the issues with leaks in the radiator core contaminating transmission fluid. But I think the better solution may be to get a new radiator if that's happening. They're supposed to be 2 separate systems so if it's mixing, something is leaking.





