Transmission / Overdrive: What Automatic Transmission Fluid do you use?

[Rhys]

I just installed a NOS Automatic Transmission in my 66 Cruiser.

Yes, as suggested by members of this group, I had the new unit serviced before the installation. (Glad I did too, it had hard varnish inside).

I certainly want to treat this unit right. What Automatic Transmission Fluid do you use and why?

Thanks in advance for all your suggestions!

[studegary]

I use Dexron in them.

[ronstrasser]

When I had the Automatic Transmission in my Avanti; a (Borg Warner Power Shift) by a local transmission shop they installed Valvoline Max Life Multi Vehicle full synthetic automatic fluid. That is what is still in it.
Ron

[rockne10]

When these transmissions first came out in the late '40s and early'50s the recommended fluid was simply a high quality 10W oil.
Modern transmission specific fluids have advanced a great deal in the interim.
I've always used Dexron/Mercon in my DGs and Flightomatics.

[Rhys]

Thanks for the replies

[gsx_martin]

I use DEXRON 3 in my 1955 President with Borg Warner DG250 transmission. It works fine

[bezhawk]

Original Flight-O-Matics used BRASS friction clutches, Those type of clutches work best with Ford Type F fluid. Most ALL rebuilds are composition clutch friction materials that a Dexron fluid works better in them. The Detroit Gear transmissions used mainly bands for friction, and fewer clutch packs. Like was said earlier, they didn't even have transmission fluid when designed, and used thin motor oil. Dexron is the modern replacement for them.

[Mike Van Veghten]

In actuality, any quality fluid will work just fine.
It's best to replace "all" of the fluid with a given type.
It's pretty much been known that for many years, that you can swap fluids.

Softer shift - use Dexron
A little firmer shift - use Type F

But even the above comments, are a little more even nowadays than they used to be.

Mike

[Dwight FitzSimons]

Is there any problem using a synthetic ATF in a Studebaker automatic? I have been using Mobil 1 lubricants (including ATF) in all my modern cars for many years with no problem. As I understand it generally AT's fail because of breakdown in lubricity of the ATF due to excessive heat. A mineral lubricant will break down at a lower temperature than a synthetic. So, a synthetic ATF would seem to be a no-brainer. Having a higher lubricity (than mineral ATF) a synthetic ATF would seem to give softer shifts than even Dexron mineral ATF. Correct or not?
--Dwight

[tsenecal]

I run Amsoil ATF in my flightomatic, but when it was rebuilt they used the newer friction material. It shifts nicely, and no leaks yet.