ATF Fluid with most heat cycle resistance?

[Carlostrece]

I'm going to make one (a pan cover) from thin copper and have the best of both worlds.

That seems a great idea. How come no one else does that? There must be a reason we're not thinking of. To easily punctured? Copper work hardening each time attachment bolts are tightened and becoming brittle?

 

[nthach]

If the Mazda can use a Dex-III fluid, I would say anything that meets the Allison TES-298/668 spec. Buses, garbage trucks and concrete mixers using an Allison transmission don’t live an easy life.

Else, auxiliary cooling. The Japanese do have thermostats installed in their ATF cooler loops, so beware.