DEX-COOL, Conventional Green, & G-05... My Experiences

"Joe Poitras" wrote

It doesn't "pump" coolant through the transmission, it just has coolant pipes running back to a cooler that sits at the rear of the transmission. I know this, because my wife owned an 87 Audi 5000 and I had to do all the repair work on it.

In this case, Audi decided to run coolant back to the transmission, instead of running trans fluid up to the radiator.

Ian

Does transmission fluid really get so hot that the hot engine coolant helps keep it cool?

I'd think that there were better ways to cool a tranny!

Approximately 10/8/03 17:05, Phrederik uttered for posterity:

Yes. Particularly under heavy load, which is why transmission coolers are so often part of any heavy duty tow package.

That *could* be politically incorrect.

Mine didn't like ethanol.

But... you CAN overcool an engine and affect performance. Can you overcool a tranny?

Not really. There's no source of moisture or volitiles to contaminate auto tranny fluid as there is in an engine (combustion blow-by) so unless you make a habit of fording streams, you don't need the oil to get hot to drive away accumulated moisture.

I suppose that if you lived in a VERY cold climate and, for example, your transmission fluid never got above freezing, you might have a problem. But as long as it gets to "room temperature" I'd think it should be fine.

Some transmissions will not lock the torque converter untill they see a certain trans fluid temp. So I'd have to say yes, it is possible to overcool a transmission. Bob

Ensure it will handle the pressure.

ATF coolers don't run at nearly the pressure that engine oil does.

I think it is actually going into 4th gear and it's the torque converter lockup that you are not feeling. They let the converter slip to purposely build heat in the trans until it comes up to operating temp. Bob