Use of multiple transmission fluid types

So I thought I would share an interesting experiment. My kids 2005 F-150 has a (4.6L) 70/4RW Transmission(Think I got that wrong, but, should make sense to you ford guys). She got stranded late at night, because the transmission dipstick tube broke in half, and was laying in the engine compartment with the dipstick still in it. It belched out a bunch of fluid, and wouldn’t move after it cooled down. She was in a bad area of town, and “AAA” said at least 3 hours to get to her. So I grabbed some cold weld, electrical tape, and all the “ATF” I had in the garage. I got to her, made the make shift repair to the tube, and added the fluids I had with me. So here is where it gets interesting. I had 3 quarts of O’reiilys Mercon-3, 1 liter of “Motul” ATF VI(Mercon LV), and 1 liter of “Motul” Dexron lll. This truck calls for Mercon V. I followed her home expecting the worst, especially after reading many posts on forums about ATF, and the many failures of this transmission in other F-150’s even with the correct fluids. In mid year 2005 Ford upgraded to the “75” version of this transmission. Even her truck had two transmissions at 60,000 miles. She’s on her 3rd one right now! Anyway, never expected her to make it all the way home. However, not only did she make it home, that eclectic mix of fluids is still in there 10,000 miles later. It seems there is much disinformation, and disagreement on what can, and cannot be mixed, and I understand that from a performance point of view, but from a blow up the transmission point of view, I’m thinking, are we being duped by all of these types of “ATF’s, and they’re approvals, viscosity’s, etc,etc,etc…? I’m thinking it’s time for a flush, but I don’t think I’ll be able to get all of it out, torque converter, pan, lines, etc… Or, if it’s still working good, with only ten grand on the fluids, should I wait a while? Sorry for the long winded story, just wanted to paint a clear pic for someone with some additional advice. Sources used so far “F-150” forum, “ Bob is the oil guy “
forum. Any suggestions would be great! Thanks a bunch. Oh… almost forgot… dipstick tube replaced with new one.

Those fluids are similar but what fluid is it supposed to take?

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So only a percentage of the “wrong” fluid was put into the trans… and from that you made the conclusion that using the proper fluid isn’t necessary.

Not trying to be flippant just stating the facts as clearly as I see them.

The trans still has mostly the correct fluid. I don’t think your conclusion is valid and I wouldn’t risk my transmission based on that.

Since your Kids’ truck has already had 3 transmissions, I doubt you’d blame the failure on the wrong fluid if it failed anyway and I wouldn’t either based on the track record of the 4R70W transmission.

I wouldn’t expect immediate trouble with fluid that is close to right.
But at 10,000 miles I think you’re pushing your luck.
I wouldn’t do a flush. Just a drain and fill. Then another a couple hundred miles later.


No, she was supposed to have a flush done ASAP, but she moved out for a while…then moved back in. I asked her if she had the tranny flushed, and she said no…as stated, It’s been 10,000 miles with that combo of fluid with no issues… at all. So my point was merely that I was surprised, and since many transmissions suffer failures after so called flushes, maybe it would do more harm than good to do it till it has more miles on it. Unless I yank the tranny, I’m never gonna get all the fluid out anyway, torque converter has to come out.

That is exactly what I was thinking. Thanks for your advice!

I don’t think it’s an issue as they are all compatible. I wonder how many cars get transmission services in which various types of fluids are used? Many or most of them more than likely.

What I would be questioning is why a 60k miles truck is on the 3rd transmission already. I also wonder how much not wanting to move was involved after it cooled down. Forcing the issue just makes things worse and can create problems that may surface later. As in transmission No. 4

My current and past 4R70Ws are and have been bulletproof.

Agreed, This third one has been the longest lasting one. As far as my opinion on the transmission type is concerned. It’s based on two things… Fords upgrade mid year, and quite a few guys on the F-150 forum crying about this transmission. Truck is supposed to take Merc V.