Type F versus Dex/Merc

[Desert Rider]

So, I took my bronco into a local transmission shop last week, and had the pan gasket and seals replaced on my rebuilt AT tranny (C-4) to hopefully stop a small leak. When I picked up the bronco, I was told that the tranny was topped off with Dex/Merc tranny fluid instead of Type F.

I asked him why he did not top off the tranny with Type F. He responded by saying that Dex/Merc is considered a "universal tranny fluid" and can be used in most transmissions; and Dex/Merc is compatible with most tranny fluids including Type F.

Am I in trouble? Can mixing cause damage? Premature wear on clutches? Should I flush? or do nothing and just drive it?

BTW, my trusted friend and expert, Viperwolf, did the rebuild/install about 2 years ago...

 

[Rustytruck]

When I took my transmission classes 20 years ago Type F was the superior transmission fluid for lubrication and performance at high temperatures it would darken but not flash over as easily.

But that was at a time when they were just starting with converters with internal clutches which used Dextron.

Dextron was better at hydraulic application but don't let it get hot, it will thin out and pass the converter seal at a high mist which is extremely flammable.

Use to see that with motor home fires back in the day.

Now that was some 20 years ago and things change just don't mix fluid. I'm sure you got the fluid you did because that's what they stock for 99% of the cars out there.

The bonded clutches are made for the newer fluids these days.

 

[Broncobowsher]

Most, if not all, of the rebuild kits have changed the clutch material to be compatible with Dextron/Mercon. Since it was rebuilt, I am going to say that it has been converted to the new fluid.

Good for checking, but nothing to sorry about.

 

[blubuckaroo]

My last tranny rebuilder said to use Dex from now on. However, I don't know about mixing them.

 

[Broncobowsher]

They will mix.

 

[Steve83]

Ford says not to.

https://www.fcsdchemicalsandlubrica...er+Steering+Fluid&category=Transmission Fluid

https://www.fcsdchemicalsandlubrica...+Steering+Fluid&category=Transmission%20Fluid

 

[Broncobowsher]

For the longest time (up through the early 90's at least) the trick for the GM guys was to put in some ford type F fluid. The friction modifier package was a bit different and the type F would bite firmer. A little bit of a shift kit in a bottle.

Now Ford who spent a lot of time and money fine tuning shifts shurly won't approve of a different shift feel.

It's a rebuilt transmission, The transmission builder isn't going to do anything to make it fail. Last thing he wants is an unhappy customer and eat it on a come back. You will be fine. I'm sure the builder used an aftermarket rebuild kit, you can throw the Ford recommendations out at that point. Follow what the kit recommends.

 

[broncnaz]

The only real difference between automatic tranny fluids is type F doesn't have any friction modifiers added to it where mercon/dextron does. The friction modifiers were added to produce softer shifts. Most likely you wont notice any difference by adding merc/dex it may shift smoother that's about it although if the tranny starts slipping then I would drain and refill with type F. Or it just could be that the tranny is about worn out.