Mercon V

9723 · Feb 4, 2011

When I got my '97 2.3 5 speed in 2004 I changed all the fluids. At the time my research showed the trans fluid.....some data stated Mercon ATF, other places stated surprisingly 5 w30 motor oil. I put in the motor oil. I've been running that since, for 42,000 miles without any issues.

Now I'm about to put Mercon V into it because ALL the data I've found say that's what I should use.

Any thoughts or experience on this subject would be appreciated.

fourwheelford · Feb 4, 2011

It may not be good to mix the two considering you can't drain every last bit out. I run royal purple in my honda and that tranny has never given me trouble. I think the mercon is to retain the warranty and it maybe handles heat better not sure though.

4x4junkie · Feb 4, 2011

I would stick with Mercon, myself (called "Dex-Merc" nowadays). Mercon V tends to cause some shifting issues on the earlier M5ODs (2008 is actually the first year that specifies Mercon V instead of Mercon).

ForOffRoadDriving · Feb 4, 2011

go with the regular mercon (DEXIII/MERC), its cheap enough that you could fill it up and drive it for a week, then drain it and fill it again, just to be sure that the 5w30 is all out of there.

Ranger Sport Honduras · Feb 4, 2011

mercon ATF is what ur supposed to use. i believe that in 03 they started using mercon V.
im using mercon ATF on my moms 03 and it has no issues. but i think it uses mercon V

TheTopher · Feb 4, 2011

There's been a few threads about this. I'm a little drunk but hopefully I'll still get my facts straight.

Basically, if you go to a ford dealer they'll sell you Mercon V and tell you that's what you need. Don't listen to them.

The older m50d trannies have copper synchros versus the carbon fiber synchros in the newer m5od trannies.

So Mercon V which is formulated for the carbon fiber will put added wear on your copper synchros and cause harder shifting.

Dex/merc is what you need.

So on and so forth...feel free to correct me if I mixed something up.

adsm08 · Feb 4, 2011

4x4junkie said:
(2008 is actually the first year that specifies Mercon V instead of Mercon).

There is also a TSB that applies to everything that says "Merc V replaces Mercon".

9723 · Feb 5, 2011

Great, Thanks!!

I think regular Mercon is the answer....turns out the puddle I was seeing is power steering fluid. I'd been moving the Ranger around so I didn't know where the puddle was coming from.

The trans however, is not leaking, but next time I change it (before too long), I'll use regular Mercon.

Thanks again!!

exbass94 · Feb 5, 2011

The power steering fluid, by the way, is also regular Mercon.

4x4junkie · Feb 6, 2011

adsm08 said:
There is also a TSB that applies to everything that says "Merc V replaces Mercon".

But does that TSB address in any way the harder "chunkier" shifting that occurs with Mercon V in older transmissions?

And why do all the oil companies (Castrol, Valvoline, Pennzoil, etc.) still continue to manufacture Mercon (now labeling it Dex/Merc) if there was no longer a need for it?

Sasquatch_Ryda · Feb 6, 2011

All he is saying is every dealership out there is now putting Mercon V in everything that used to call for Mercon as we no longer stock Mercon.

4x4junkie · Feb 6, 2011

I completely understand that (didn't mean it to be argumentative if it came off that way).
All I know is my friend had the oil in his '93 M5OD changed at a "quick lube" shop a few years ago... They put Mercon V in it following this TSB thing and within about 500-1000 miles, he started having problems shifting gears (was not the clutch... that was the first thing we checked). I put std Mercon back in it and it improved somewhat, though it never did fully return to how it was before.
My BII's M5OD I suspect also had V in it before I got it. I checked it over real well before installing it, everything such as synchro clearances were all very much within the tolerances outlined in the manual, yet it exhibits some of the same symptoms my friend's has (chunky shifting, and occasional difficulty getting it into gear when stopped).
I've seen others complaining about this here and on other sites as well. :dunno:

9723 · Feb 7, 2011

Yes, mine also shifts real tight on either side of 2nd....and getting it into 1st at a stop sign can be problematic. I always figured it's just that line of trans. 'course, I got my Ranger at 108k miles. Now it's got 142k....hasn't changed.

Just a note: I put in the K&N cold-air system and Accel Hi-Pro coils because I run it nearly the width of Texas on I-10 3-4 times per year.....I run it all the way at 84 mph. That lil' 2.3 likes it. Only about 19 mpg at that speed, tho.

Mercon V

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