what fluid is best for my M5OD transmission?

preranger94 · Sep 28, 2010

I rebuilt it yesterday and have heard a lot of good things about synthetic fluid. what do you guys recommend?

L454S · Sep 28, 2010

Atf

I am running Mobile 1 Synthetic ATF in my 2010 now. It shifts the same as with the factory fill. Mobile 1 was one of the only ones I could find locally that had the Mercon V compatability label. If my unit was out of warranty, I would try one of the better MTL's available like Redline or GM Synchromesh.

Yellowsplash · Sep 28, 2010

You can use mercon V, but it calls for mercon.

hondaxr650 · Sep 28, 2010

They all get MERCON V in our dealership.

Captain Ledd · Sep 28, 2010

1997 Ranger/Aerostar Ford Factory Service Manual says:

Transmission AND Transfercase:
Motorcraft MERCON® Multi-Purpose Automatic Transmission Fluid XT-2-QDX (or -DDX) or equivilent.

Straight out of my book in the shed for manual transmissions.

pcollins · Sep 29, 2010

Seeing as Ford phased out Mercon, its Mercon V. or Some good synchromesh fluid.

WTF · Sep 29, 2010

Royal Purple Syncro-max. :beer:

4x4junkie · Sep 29, 2010

Mercon V seems to cause shifting issues in a lot of M5ODs. I'd just stick with what's recommended (it's now labeled "Dex/Merc" on the bottle since Ford started playing their game with the licensing of the name).

freerider6_9 · Sep 29, 2010

TSB 06-26-1

01/08/07

MERCON ATF IS BEING REPLACED BY MERCON V
AS A SERVICE FLUID FOR SOME MANUAL
TRANSMISSIONS

FORD:
1981-2003 Escort
1984-1995 Thunderbird
1985-2007 Mustang
1985-1996 Bronco
1985-2007 Ranger
1986-1997 Aerostar
1991-2004 Explorer
1995-2007 F-150
1996-2007 F-Super Duty
2001-2003 Explorer Sport Trac, Explorer Sport

LINCOLN:
2001-2002 Lincoln LS

MERCURY:
1984-1995 Cougar
1987-1999 Tracer

ISSUE
MERCON(R) Automatic Transmission Fluid is being replaced by MERCON(R) V as the service fluid for manual transmissions originally requiring MERCON(R).

ACTION
Beginning immediately all manual transmission applications requiring MERCON(R) can now be serviced using MERCON(R) V or MERCON(R) Automatic Transmission Fluid or dual usage fluids labeled MERCON(R) / MERCON(R) V. After July 1, 2007, MERCON(R) Automatic Transmission Fluid will no longer be manufactured, therefore, availability of this fluid will continue until remaining inventory has been depleted.

4x4junkie · Sep 30, 2010

Yeah it seems to be too slippery for the synchros on older M5ODs.

What's odd is just before that, Ford actually warned not to use Mercon V in Mercon apps (would void warranty), yet now they say it's all OK. :icon_confused:

gw33gp · Sep 30, 2010

WTF said:
Royal Purple Syncro-max.

I have been using Royal Purple Syncromax for over 60,000 miles with good results. I think the shifting is slightly better than with the original factory fill.

exbass94 · Sep 30, 2010

4x4junkie said:
Yeah it seems to be too slippery for the synchros on older M5ODs.

What's odd is just before that, Ford actually warned not to use Mercon V in Mercon apps (would void warranty), yet now they say it's all OK.

At first Mercon and Mercon V were 2 completely different fluids, then Ford realized it was redundant to have 2 seperate fluids when 1 fluid could do it all, so they reformulated Mercon V to make it backwards compatible with Mercon, and stopped licensing Mercon.

4x4junkie · Oct 1, 2010

Well, from what I've seen it doesn't do it all. I will stick with the old Mercon (Dex/Merc), though I might also be open to trying something like that Syncromax fluid maybe too.

Some here have reported good results with 0W-30 synthetic engine oil in the M5OD too.

AllanD · Oct 3, 2010

4x4junkie said:
Yeah it seems to be too slippery for the synchros on older M5ODs.

What's odd is just before that, Ford actually warned not to use Mercon V in Mercon apps (would void warranty), yet now they say it's all OK.

It's actually not that it's "too slippery" it's that it's too thin for the earlier manual transmisisons without creating noise and shift quality issues.

Now that being said the 1998-up manual transmssions use completely different synchros and these were specially designed for MerconV fluid.

AD

Railranger · Nov 10, 2010

4.o with a 5 speed for towing

I am changing my trans (5 speed) fluid, and when drained it was pretty metallic, the drain plug had alot of metal attracted to it. It scares me!!

So has anyone used any heavier oil in the trans?

I have to admit that i made a mistake a few years back and filled it with 80-90 gear oil, I drove it for 3 months daily before I realized and changed back to atf. I noticed no problems.
I am wondering if anyone has ever tried using heavier oil and what the downsides could be?
I use this truck primarily for towing a camper trailer.
Thanks Y'all

what fluid is best for my M5OD transmission?

New Member

New Member

New Member

New Member

Well-Known Member

New Member

New Member

Forum Staff Member

New Member

Forum Staff Member

Well-Known Member

Well-Known Member

Forum Staff Member

TRS Technical Staff

New Member

Sponsored Ad

Sponsored Ad

Member & Vendor Upgrades

Truck of The Month

Recently Featured

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store

Sponsored Ad

Sponsored Ad

Sponsored Ad

Amazon Deals