ATF: Type F vs MD 3

IFHP · Post by **IFHP** » Sat Jan 19, 2008 1:13 am

Today my father-in-law and I changed out the ATF and replaced the filter in my 1972 F-100 (C4). When we were two quarts in to refilling the transmission, we noticed that the Chevron ATF that were were using was MD 3 (formerly Dextron III). The dip stick says to use only Type F. He had a couple quarts of Type F in his shop, so we did a visual comparison, pouring Type F and MD 3 in to white cups -- they look identical.

My question is, does it matter? Should we drain the new MD 3 out and replace it with Type F, or just fill it with MD 3 and call it good?

What do people think?

Thanks,

Michael

carnuck · Post by **carnuck** » Sun Jan 20, 2008 12:08 am

Dex 2 and 3 are equivalent to 5W30
Type F is more like 10W30 (it's stickier)

IFHP · Post by **IFHP** » Mon Jan 21, 2008 2:09 am

Thanks, we ended up putting 8 quarts of Type F over the 2 quarts of MD 3. I'm hoping for the best.

Michael

l1k2gadd · Post by **l1k2gadd** » Tue Jan 22, 2008 10:55 pm

Someone, years ago, told me that when you accidentally add Dextron (older Dextron of the 80s and 90s) into a Type "F" tranny the Dextron will cause early deterioration of the seals inside of the tranny. It won't be something you will see right away, but within months of the addition of the wrong fluid. The two, supposedly didn't go together (mix) in the same tranny, hence the dip stick being imprinted with the warning to use only type "F" fluid.

I would seriously look into this by contacting a couple of tranny shops, OR more than a couple, to see what they say.

I'd hate to see you lose the tranny over the two quarts being in there.

(edit) Contacting one of the brand name tranny fluid manufacturers Tech Sites by e-mail or by phone to a customer service office (then to a tech dept) might be good also.

sideoilerfe · Post by **sideoilerfe** » Thu Jan 24, 2008 2:08 pm

Do not mix it!!! You will loose 2nd gear!

I had a C6 that leaked when I bought it and the PO topped it off with Drexon. It started acting funny between 2nd and 3rd. Few months later....no second gear.

I had another truck with a C6 that I changed the radiator and lost a quart from the cooler. I added Type F and It started shifting funny from 2nd to 3rd. I didn't think anything of it until it lost 2nt gear! Then I started to put 2 & 2 together.

Never mix it!!

Banjo · Post by **Banjo** » Thu Jan 24, 2008 8:10 pm

I thought the reason type F was stamped on dipstick was that dextron was not even made back then, but I may be wrong. I have heard you should not use dextron in older transmissions with the old parts in them, but you could use it in rebuild Ford auto's. Something about the rebuilds having seals made of different material that you could use Dextron in.
I have also heard you could also use type F in the newer rebuilds and it would make shifts firmer. Disclaimer: these are things I''ve read and I do not know for sure. Just throwing out to see what others say. I am confused on the post that says they used Dextron in a C6 and lost 2nd and then used Type F in a C6 and lost 2nd? Or I mayb e reading it wrong.
Banjo.

Banjo · Post by **Banjo** » Thu Jan 24, 2008 8:14 pm

ok, just re-read, the guy above was saying if you mix the two you'll kill a C-6. If that is so, mine should go at some point, I know I accidentally bought a quart or two of Type F and put into my 5 year old rebuilt C6 that I'd previously filled with Dexron.

sideoilerfe · Post by **sideoilerfe** » Thu Jan 24, 2008 9:28 pm

Banjo wrote:ok, just re-read, the guy above was saying if you mix the two you'll kill a C-6. If that is so, mine should go at some point, I know I accidentally bought a quart or two of Type F and put into my 5 year old rebuilt C6 that I'd previously filled with Dexron.

Does it shift differently from 2nd to 3rd than it did before? That is what my problem was so I think it had to do with the mixing of the two. The second truck with the radiator swap, worked perfect until I added the type F to the Drexon mix.

fordman · Post by **fordman** » Thu Jan 24, 2008 9:43 pm

dex 3 is ok in newer fords. it can be used instead of type f in older transmisions. i dont know if you can mix them. dex 1 and 2 are not for ford use ever.

l1k2gadd · Post by **l1k2gadd** » Sun Jan 27, 2008 7:40 pm

Most newer Fords require Dextron. In the 70s and 80s, as I remember it, Dextron was GM's transmission fluid and I believe the '69 Camaro I owned for a while used Dextron. I believe the "F" in Type "F" originally was a neumonic that represented Ford.

(Edit) Type "A" transmission fluid could be used in conjunction with Type "F" and Type "A" transmission fluid could also be used in Ford power steering systems (back then).

IFHP · Post by **IFHP** » Sat Feb 02, 2008 4:11 am

Oh, a lot to think about here. Thanks for the warnings and advise!

Michael

fordman · Post by **fordman** » Sat Feb 02, 2008 1:25 pm

i should have posted dex 3 or also called dextron mercon. dont mix type a with type f.

averagef250 · Post by **averagef250** » Sat Feb 02, 2008 10:04 pm

I think the original seals used were of a material that agreed with the type F only. If you used dexron in an original you could maybe, possibly, but more than likely not have problems.

You can run old autos on anything. light motor oil, tractor hydraulic fluid, etc. they really don't care that I've seen.

Dexron is the standard nowadays.

I buy the stuff by the barrel and it's not even dex3, it's just specified as "dexron ATF". It's the equivelent to dexron 3 and I buy pint bottles of additives that transform this dexron into the new dex5 and fancier stuff so I don't need to have lots of different fluids on the shelf.

That said, I don't believe the new ATF's are full synthetics. Since you can use dex3 with the proper additive to make anything you want.

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