904 Transmission Fluid Recommendation

S.Rodney said
I know this thread hasn't been updated since 2012 but I got information that I think is relevant to this discussion.

One of the Dodge (FCA) dealership in Quebec City (JD Chrysler de Boischatel) is also a Mopar Service point. So, I contacted them to have their expertise (the Mopar service guys) and the director of their parts department owns a Dodge Dart 1974 like me.

I've asked the following: Knowing that the Dodge Dart 1974 owner's manual mentions "Dexron only" and that Chrysler switched from Dexron to ATF+4 in the 2000's what is Mopar's recommended fluid for a Torqueflite 904/727 ? (I've also mentionned that on some forums, such as this one, people claim that Type F has sharp shifts, that Dexron III destroys the TF or is the fluid of choice... that ATF+4 is superior, etc... lots of contradictory opinions).

His anwser (the original answer in French):

The English traduction:

I've made my own research on that topic and, after gathering all the needed info, will use Dexron-VI (full-synthetic) from licensed manufacturers. (Petro-Canada makes the original product for GM's own AC Delco).

So, look for a Dexron GM License number on the Dexron bottle you buy, you'll be 100% guaranteed the product is compliant with the actual spec, which is fully retrocompatible with previous Dexron specs.

The Dexron 6 is a full synthetic ATF that uses a certain quality base stock. If the ATF+4 is overkill then certainly the Dex 6 is! You won't prematurely wear out your transmission by using a synthetic ATF in a 904 or 727. However it really isn't necessary for anything but the most stressed applications because the older TF transmissions don't have as many gear sets stuffed into a smaller case like the newer vehicles so there isn't a much heat vs amount of fluid to cool them. You won't hurt it but it isn't giving you that much benefit for the cost.
As for the type F fluid being just for Fords that's bullshit. The transmission doesn't know if it's a Ford or a Chrysler. They use the same friction materials and steel gears. The reason why it's used in Chrysler and GM cars is because it doesn't have the friction modifiers(makes things more slippery) like the Dexron fluids do so you get quicker grabbing of clutches and bands which = quicker firmer shifts. Less slippage means less heat too.
The newer fluids (+4, Dex V, Dex VI etc) are designed for longer intervals between changes and because of the heat generated by the more modern transmissions with 4,5,6 7 speeds and up. Since most of the classic car owners tend to over-maintain our vehicles conventional Dexron III or type F is fine. The more expensive synthetics aren't needed.