Couldn't find a definitive answer.

I have a 1977 Ford F-150 w/ the original C6 automatic that was rebuilt by AMCO (by previous owner).

I am going to be replacing the hoses and the transmission fluid, hasn't been done since I've owned it, hoses are old, etc.

I am unsure what type to use. I believe the previous owner used the mercon ATF, I thought it needed the Type F fluid?

I am getting conflicting reports from the auto stores here in town as 1977 was the model year that Ford made changes to the type used?

So, what type is correct for my truck? Is it bad to run the mercon ATF? to run the Type F?

If the mercon type is wrong, do I need to flush it completely? Or can I just start adding Type F to it from here on out? (it is a bit low now). Is it bad to mix the two types?

Thanks for the help.

Eric

 

I was thinking Type F. Post in the tranny forum as well.

 

pull your tranny dipstick out. it should say what type of fluid to use on the dipstick, my 77 f250 says type f, but i have seen others that say to use mercon. but id do what the dipstick says. if it says nothing, id use type f. thats what all my trucks get.

 

Use,
__the MERCON ATF; hence it was rebuilt.
Once the tranz has been rebuilt it can use the mercon atf.

If it hasn't been rebuilt, it will need TYPE F.

I repeat, you do not use the TYPE F fluid.
Use the MERCON ATF.

You CONNOT mix tranmission fluids, this is bad to do!
Any well educated transmission shop will tell you the same.

 

Wrong.

AS ORIGINALLY EQUIPPED:

1977 and later C4/6 uses Mercon from factory.

1976 and earlier uses Type F from factory.

This is written in stone.

 

I believe the difference is in the newer clutches, seals etc. i.e. newer or rebuilt units would have the newer fluid. I do hear that type "F" only gives you stiffer shifts.

 

i made this mistake. i read the books and assumed my auto was a c4 behind my 302. blew a cooler line *ghetto rigged i discovered* bought and put in type F and later correctly identified the c6 via the pan, changed the fluid and filter and have ran mercon ever since. haven't had any problems post rebuild *cooler was COMPLETELY clogged, hence the blown line* running mercon. as far as i've ever read, the c6 has always used mercon.

 

hence prolonging the life of your tranny. I run type F in everything.

OK everyone LET ME HEAR IT!

 

i have to agree on type f in everything... all my trucks have always and will always get type f, both in transmission and powersteering... i have yet to have a problem resulting from useing type f.

 

Got a 79 C6 with over 205,000 miles, flushed twice using type F, never a problem and no leaks. While my engine is being rebuilt, I've had the tranny rebuilt also and will go back with type F unless the rebuilder says otherwise.

 

VERBATUM from the 1973/79 Ford Light Truck & Passenger Car Parts Catalogs:

XT-2QDX .. Automatic Transmission Fluid "MERCON"

For use in 1977/ C4 & C6 Automatic Transmissions.

The back slash after 1977 means 1977 and later.

 

You're correct, after checking my records, I found I'm using Dextron II in the transmission and Type F in the power steering.

 

This is how I heard it too.

 

Ok,
__here we go again.

1. the shop that rebuilt it filled it with MERCON.

2. If an early make C4/C6 tranz is completly rebuilt you have a choice of what ATF you can use. (Later models use Mercon, As stated by N.D.)

What ATF you use depends what type of shift & life the tranz has.

MERCON : Softer shifts, thicker fluid, & longer life span.

Type F : Harder shifts, thinner fluid, & has a not so good life span.

I recived this infomation from a teacher & repair tech of transmissions of 30+ years.

He still repairs transmissions in his own shop, for extra cash.

I call him when I need infomation on any technical issues or just need a rebuild.

__________________________________________________ _____________

If you find any proof that I or my research is wrong, please prove it.

P.S. Stone can be broken'.

 

I found this on Mobil 1's site for what it's worth. Personally I think I would go with the F for firmer shifts if it were mine.

Applications
The frictional characteristics of an automatic transmission fluid are an important factor in the design and operation of the transmission. All Ford Motor Company transmissions built prior to 1977, and certain models that continued in use during 1977-1980, were designed for a high-friction fluid that allowed the shifting clutches to lock up or engage quickly. Ford specification ESW-M2C33-F covers this type of product, which is commonly referred to as "Type F" fluid. Mobil ATF Type F is the appropriate product for these units.

These Ford vehicles are identified as:

All 1976 and earlier Ford, Lincoln, and Mercury models of cars, vans, and light trucks.

All 1977-1980 Ford models having either ESW-M2C33-F or no number at all stamped on the transmission dipstick.

Mobil ATF Type F is not recommended for automatic transmissions in Ford, General Motors, Chrysler, American Motors, or any other cars requiring a Dexron-II, Dexron-IIE, Dexron-III or Mercon-approved fluid, or for those Ford products requiring an M2C138CJ (Type CJ) fluid or an M2C166H (Type H) fluid. For the above applications, Mobil ATF D/M (Dexron/Mercon) or Mobil Multi-Vehicle ATF are recommended.