Ford F250 Tranny fluid - What to use?

ford
f250
transmissions
fluids

#1

We have a 2008 Ford F250 with a 6-speed manual 6.4L turbo diesel engine. The transmission shifts a little hard and we wanted to change the tranny fluid, but the owners manual recommends 2 different fluids to use. Which is the best one: The Ford synthetic manual transmission fluid or the Mercon V ATF?


#2

There are TWO different transmissions, that’s why.

Tell me the last eight digits of the VIN and I can look it up.


#3

ken is absolutely going to be the expert here - and I would go by giving him the last 8 of the VIN to make sure you get it right.

But it seems to me that you use the manual t fluid if its a manual/standard and the Mercon V if its an automatic. Since your concern is hard shifting we’d have to assume an automatic and that makes it Mercon V. But I just noticed that you said manual. You don’t put the same kind of fluid in manuals & automatics.

What I’m wondering is whether you can describe how a manual shifts a little hard. Do you mean harsh engagement? Or do you mean that the shifter doesn’t move freely?


#4

The ZF manual trasnsmissions used to and may still call for ATF (Mercon/DexronII or III) We used to use the synthetic ATF because it did make for smoother shifting. You can feel it is more slippery to the touch than the non-synthetic…expensive, but worth it.


#5

The last 8 on the VIN are 8EA50997. Thanks!


#6

By hard shifting I mean it doesn’t go into 1st very easily, especially when its cold and the RPMs are between 500 and 1500. It does get better as it warms up, but since we bought it used, we don’t totally trust what maintenance was done before we bought it.


#7

The ZF M6HD-W 6speed manual transmission should have the
full synthetic manual transmission fluid.
motorcraft part # XTM5QM.


#8

Back in the day of the 5-speeds, I replaced many 5th-reverse synchros on diesels because of the lame shift pattern:
1-3-5

  • N -
    2-4-R
    Many folks would hear the engine running at high RPM and just by nature, reach for anoth gear. That would happen to be reverse. At 60+ MPH, that did a quick disservice to the reverse blocking ring made of sintered iron. They should have left reverse unsynched or made an alternate shift gate for it. I should think the 6-speed is better. For 2011, Ford has eliminated manual transmissions altogether for the F250+ series. Frankly, I think it is a wise move.

#9

Thank you! Do you happen to know what the factory fill was for this tyranny? I’m sure you can see why this would be confusing since the original diesel supplement said MERCON V ATF but the owners manual said Ford full synthetic.


#10

Early on, it was non-synthetic. Later…I think '95+, it was synthetic. You can tell by the synthetic’s slipperiness. Sytnthetic also has a very sugary-sweet smell.