Besides coolant leakage into the motor oil and combustion chamber, as 911LE described, it can also leak into the transmission fluid.

 

Correct. And if that's the case then only the radiator needs to be replaced. Usually it is the other way around and there is trans fluid in the radiator as that system is at a higher pressure.

 

When you replaced your thermostat, did you orientate the jiggle valve on the thermostat at 12 o'clock? I am not sure if this in even necessary, but I just changed my t-stat and I didn't pay attention to where I placed the jiggle valve. I have been having overheating issues and have been trying to troubleshoot it. I read something in the older gen forum about the jiggle valve placement so I thought I would ask.

 

I know that is an important issue and should be done, but my problem was the fact I should have added coolant/water when the heater was on full blast. I just had an air bubble and a failing passenger side radiator fan motor.

Tom in Dallas