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M5OD-R1HD what is the correct fluid?

  • Thread starter Thread starter Mike Tonon
  • Start date Start date

Best fluid for the M5OD-R1HD transmission is...

  • Synthetic parts store ATF

    Votes: 0 0.0%

  • Total voters
    6

The frames on the newer ones are more prone to rust than the older ones, and the older bodies are more prone to rust than the newer ones. Just what I have seen anyway. Pretty common to see nice looking late model trucks with a frame that's ready to fall apart.
 
Passenger side always catches more crap.

Balljoints and wheel bearings will usually go on that side first. More potholes along the curb to pummel suspension components. More puddles along the curb for salt spray.
 
For the love of #^$^# just buy some fluid and put it in your transmission. This thread past useful 3 pages ago. Its obvious you are going to do what you want, or are just randomly trolling.
 
For the love of #^$^# just buy some fluid and put it in your transmission. This thread past useful 3 pages ago. Its obvious you are going to do what you want, or are just randomly trolling.

No, I’m just trying to get the info. That’s all. I couldn’t find this stuff before. I’m thinking it’s probably from before the Mercon V changeover. What is the shelf life of synthetic ATF? And does this stuff compare to Mobile1 synthetic?
 
Bottles look old to me, I would pass. Especially at $18/qt.
 
A friend of mine had put Mercon V into his '93 M5OD many years ago... Within a week he was having issues with shifting (hard to get it into gear while stopped, and chunky or notchy shifts while driving) (this was NOT a clutch issue, he actually still has the same clutch in it today). I've also seen others report similar issues shortly after Ford was flip-flopping back & forth about whether Mercon V was backward compatible with Mercon or not before finally deciding on that it was.

There are also some people who have used Merc V and not reported an issue, however I personally wouldn't chance it on any M5OD manufactured before 2008 (the first year Ford began the recommendation of Merc V for the M5OD). Seems there is a reason Mercon remains on the market as "Dex/Merc", which is what I'd use in any case (that or a synthetic MTF like Royal Purple Synchromax).

My belief is that there is an additive in Mercon V (not present in Mercon) that is too slippery to allow the transmission synchros to function properly.
 
Ok, I found out I had a quart of parts store brand Mercon left over from a job years ago and I also bought a couple quarts of Royal Purple ATF. I’m going to throw those in. I gotta try the RP, I’m curious what it will be like with that. Thanks everyone!
 
Whoa! You cant mix straight mercon and royal purple!!!!!
 
Whoa! You cant mix straight mercon and royal purple!!!!!

It says compatible.

And if it’s true what some have said about using synthetic being too slippery, I guess I should do about 30% regular atf. Best if both worlds.
 
It says compatible.

And if it’s true what some have said about using synthetic being too slippery, I guess I should do about 30% regular atf. Best if both worlds.

You need at least 20% type F with mercon in order to use 70% synthetic multi formula. And I would still use 50% lucas.
 
I'm running 1 quart of Royal Purple Synchromax and 2 quarts of store brand Dex/Merc. It works great.
 
It’s in! Since yesterday, I’ve had 2 quarts RP and about .8 quarts store brand Mercon, that I had left over from years ago. It feels about the same, shifting. The stuff that came out was Mercon V. It was still red, but metallic. The magnet on the drain plug had about 1/16 inch of metal debris stuck to it. I draining and refilled the transfer case, too. 1 quart synthetic transfer case fluid and about .2 quarts Ford transfer case fluid, that I had left over from last time. Then I had some of that Mercon, some Mercon V and a few drops of RB, together about half a quart. So I sucked out my power steering reservoir with a turkey baster and filled it back up with my new mixture. The stuff in there smelled a little burnt, but was bright red.
 

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