. trans fluid education needed

[66hcs-conv]

Hi gang,

Changing the trans fluid in the '66 Mustang - C4 auto transmission.

I am trying to determine the correct fluid to put back in. The manual I have says to use Ford spec M2C33D, which I belive is Type F. BUT all I can find is
M2C33F, which I believe is Type FA.

Is the type FA a newer version of the old type F, and will it work in the 1966 C4 transmission?

THANKS for your help, Dave

 

[Russ]

I know this will cause a stir, but I always use synthetic ATF in my classic Mustangs and other cars. It works well, and you will not have to change the fluid at the 30,000 mile (!) interval. Most synthetics can be used in a variety of applications (Type F, Dexron, etc.). I'm waiting for the others on the website to chime in. Hope this helps,
Russ

 

[dalorzo_f]

No expert, but there are differences in viscosity/content for specific applications.

As an example Ford does not recommend Type F for Mercon-era cars.

Type FA is a replacement for Type F, very similar.

Have seen some posts/info concening premature wear and slipping in older transmissions built for Type F using newer fluids, not sure if it marketing/PR, opinon and conjecture, or real...

I would expect if rebuilt properly with compatible seals/adjustments an older C4/C6 could be upgraded for newer fluids...

If its an older trans and just changing fluid, me, I'd stick with Type F or FA if that's what was in it before.