1957 Mixing Type F Transmission Fluid with Dex/Merc

[doug7740]

As the attached article states; if your transmission was overhauled over ten years ago, you are probably using type “F”. A recent overhaul would have used Mercron Dextron III. If you do not know for sure which type of transmission fluid is used in your car, the best thing to do is to have your transmission and torque converter drained completely of existing fluid.

I’m not an expert on transmission fluid, but I have overhauled quite a few automatic transmissions. I have also attached a few articles on this topic in the past. From what I have read it is not advisable to mix different types of transmission fluids. I don’t know if that is true or not and I would like to see some articles indicating that they can be mixed, but until then I’m not going to mix the different types of transmission fluids.

doug7740
1955 Thunderbird Blue

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[Brax]

Absolutely, When I replaced the transmission fluid and filter on my 1955 Thunderbird I used Type F transmission fluid. As I said, Type F transmission fluid is not hard to find. At least where I live.

doug7740
1955 Thunderbird Blue

Type F is the wrong fluid, type A or Dexron 1-2 or 3.type is correct, type F is for select ford transmissions I believe until 78. F doesn’t mean Ford,

 

[doug7740]

Type F is the wrong fluid, type A or Dexron 1-2 or 3.type is correct, type F is for select ford transmissions I believe until 78. F doesn’t mean Ford,

Brax,

Why is type F the wrong fluid? As per the articles that I have included it states:

Transmissions began using Type A fluid in the late 1950s. Type A evolved into Type A Suffix A, and then into Dexron; however, each of these iterations relied on a sperm whale oil additive to act as a friction modifier, at least until the use of whale oil was outlawed in the early 1970s.

Ford first produced its own transmission fluid formulation in 1967, referred to as Type F or Type FA. The name comes from Ford’s specification number for the fluid, ESW M2C33-F. This fluid was used in all Ford transmissions until 1977 and most Ford transmissions until 1980.

doug7740
1955 Thunderbird Blue

 

[Brax]

Brax,

Why is type F the wrong fluid? As per the articles that I have included it states:

Transmissions began using Type A fluid in the late 1950s. Type A evolved into Type A Suffix A, and then into Dexron; however, each of these iterations relied on a sperm whale oil additive to act as a friction modifier, at least until the use of whale oil was outlawed in the early 1970s.

Ford first produced its own transmission fluid formulation in 1967, referred to as Type F or Type FA. The name comes from Ford’s specification number for the fluid, ESW M2C33-F. This fluid was used in all Ford transmissions until 1977 and most Ford transmissions until 1980.

doug7740
1955 Thunderbird Blue

type F has greatly reduced anti friction additives, and was designed for the material used in clutches and bands hence the more positive harsher shifts, Ford stated use only in transmissions designed for type F, type A is essentially Dexron and just like posi traction additive that relied on whale oil outlawed new anti friction additives were introduced. The article you posted actually says the same thing and it’s one opinion at the end that says what you are saying. The use of Type F in type A or dexron transmission will produce harder shifts but at the price of increased transmission wear because of the lack of anti friction additives. Sure a car driven on an occasional weekend the wear is slower but still there. Type A is available as well as Dexron 2 and 3. Ford never made type F a universal fluid for all Ford transmissions during the 60s or 70s. The point of your article is yes you can use it but at your own risk but states Type used in most auto transmissions of all manufacturers evolved into dexron and is the correct replacement, In my opinion why not use the correct Type A that is still available or Dexron 2 or 3. When I rebuilt transmissions I know the he material used and the correct type fluid to use. Transmissions lasted 100k miles or more in the 50-70s using type A they were designed for why would I want to change that, sure you want harsh shifts use Type F but there’s a price to pay down the road.
Just as a aside my 1970 Torino cobra drag pack owners manual with C6 transmission obviously calls out type F only for transmission but Ford states to use something different in PS (Power Steering Fluid Spec ESW M2C128 A) spec for type A in the power steering pump ,if they were the same why type not use the type F in the PS the reason is the anti friction additive in type A/dexron. Just my 2 cents and having lived in 60s and 70s