Guys, my 69 F-100 has a C6 transmission that has suddenly stopped changing up out of 1st into 2nd and 3rd. I checked the fluid and it is on the add mark.

Is it supposed to take the type F fluid or Dexron? I don't have any type F and am not sure of my local auto spares store has any either. Would it hurt topping it up with Dexron?

 

Use type F, unless you know the tranny has been rebuilt with innards made for Dexron. AutoZone has type F under their house brand label.

 

Oreillys carries type F too.

 

Thanks for the info on which fluid to use. I'm in the UK though,so no Autozone or Oreillys for me. But, I have found a couple of sources for type F online so will be ordering some in.

 

Order a case or two. You will need it eventually depending on how long you keep the truck.

 

Our trucks originally used type F as power steering fluid as well. I don't know how much difference it would make to run regular power steering fluid in place of type F, though.

 

I've heard of it causing some problems but I don't know the specifics.

 

Probably with the seals. Power steering fluid has more "conditioners" I guess you'd call them. Probably would swell the old seals and cause them to blow out.

 

For one thing type F is less foaming additive in it.
So it may help keep the PS pump quieter..
Orich

 

The C6 I have has fluid that looks like it ought to be changed. It has a shift kit in it and it shifts hard. How do I know if it has Type F or Dexron fluid?

It's in a 67 F100 behind a 460 and neither of those are stock items.

 

That's the thing......how do you tell what's already in there and also what mods have been done to the transmission by previous owners, that might have set it up to work with Dexron?

Anyway, I topped up with about half a litre of Dexron yesterday as I had no type F, plus fixed a bad vacuum seal going onto the modulator and it's working again. I have some type F on the way so will top up with this in future. Plus my PS pump is quite noisy so I'm thinking maybe that is filled with Dexron when it should be type F.

 

That's a good question. Maybe a parts store could analyze it?

 

Heck, If a shop put in the shift kit then, I'd figure it's Dexron ..
Orich

 

I remember that one of them is slicker than the other...just can't remember which on is. Anybody know which one is slicker?

 

Well I know Type F has friction compounds in it...