TH400 Transmission, Stock Converter Aluminum Cooler Lines to Stock Radiator ATF Cooler Inline Transmission Cooler on Return Line into Transmission Derale Deep Steel Pan with cooling tubes inside What's the optimum ATF temperature for daily driving? I heard 200* degrees is fine, anything over that is bad. Engine Temp stays around 180-190* degrees, so the ATF temp can only go up from there. I figure with the external inline cooler and tubed deep pan will drop ATF temperature quite a bit. Just trying to be preventative, no such thing as overkill, right?