# Installing an aftermarket ATF cooler



## monkeytronic (Oct 5, 2009)

I'm in the midst of planning a complete change of every fluid in the '02 A6 4.2 as it's now at 80k miles and I'm wondering if there are any issues to be had with installing an aftermarket oil-to-air ATF in series after the factory oil-to-water ATF cooler in the radiator so that both coolers will be plumbed in series.
On all the other cars I've done this on, notably older Fords and newer Volvos (the latter sporting GM-sourced transmissions) that use either Dexron-III or Dexron-VI ATF, I'd just install the aftermarket ATF cooler and be done with it but with the A6's ZF-sourced 5HP24 automatic I'm wondering if there'd be problems considering that the transmission doesn't use any flavor of Dexron ATF and the transmission is filled and the ATF level checked from under the ATF pan at a specific temperature.
Basically I'm worried if _over_cooling the ATF will be an issue. FWIW I'd plan on installing a stacked-plate ATF cooler similar to the usual B&M Racing or Derale unit featuring an internal fluid bypass and no external thermostat unit of any kind.


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## frankinstyn (Oct 11, 2004)

*Re: Installing an aftermarket ATF cooler (monkeytronic)*

I don't know about the answer to your question but do have to ask....

Why bother? These transmissions are not known for having problems with overheating at all.


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