Stupid question: Best fluid for M5OD...and any additives?

[Garth Libre]

I wonder if this settles the issue. Castrol says for the M5OD transmission they recommend Transmax Mercon V https://www.castrol.com/en_us/unite...b5eef3aea3cea74&component=transaxle-automatic

 

[Garth Libre]

I just came back from Autozone, ORielly's, and Walmart. None of them have Transmax Mercon V. Instead I saw Castrol's Transmax for import cars with no marking on the container that it is Mercon V.

 

[Garth Libre]

I don't understand the confusion. My owners manual that came with the 2010 car in the glove box says use Mercon 5 in the manual transmission. Why is this being questioned?

 

[JohnnyO]

Redline D4 ATF since it calls for Mercon. Either Amazon or Summit Racing. I used it in the Mustang my son used to own and it shifted better. Had some left over so I used it in the transfer case of my old Sport Trac.

 

[Roert42]

I use normal Mercon V. Motorcraft if I order online, Valvonline or store brand if I have to buy in store.

 

[4x4junkie]

I don't understand the confusion. My owners manual that came with the 2010 car in the glove box says use Mercon 5 in the manual transmission. Why is this being questioned?

The confusion comes from a 2007 directive from Ford that claims Mercon V fluid is backward-compatible in applications calling for Mercon fluid. While Mercon V does seem to be OK in automatic transmissions that originally called for Mercon (such as the A4LD), this hasn't been the case with the manuals. There have been a multitude of reports (and I have witnessed this myself) of hard shifting occurring on M5OD transmissions after changing the fluid to Mercon V.

This is very likely why Mercon fluid continues to exists in the aftermarket as "Dex/Merc" and other brandings such as "Multi-Vehicle ATF" (this because Ford at the same time also decided to yank the license to sell the fluid under the "Mercon" trademark).


Since you have a 2010, there shouldn't be confusion (Ford actually made the recommendation for Mercon V for yours).
However with a pre-2008 truck, I would strongly suggest sticking with what was originally specified for it (which would be Mercon, a.k.a. Dex/Merc).

 

[Garth Libre]

The confusion comes from a 2007 directive from Ford that claims Mercon V fluid is backward-compatible in applications calling for Mercon fluid. While Mercon V does seem to be OK in automatic transmissions that originally called for Mercon (such as the A4LD), this hasn't been the case with the manuals. There have been a multitude of reports (and I have witnessed this myself) of hard shifting occurring on M5OD transmissions after changing the fluid to Mercon V.

This is very likely why Mercon fluid continues to exists in the aftermarket as "Dex/Merc" and other brandings such as "Multi-Vehicle ATF" (this because Ford at the same time also decided to yank the license to sell the fluid under the "Mercon" trademark).


Since you have a 2010, there shouldn't be confusion (Ford actually made the recommendation for Mercon V for yours).
However with a pre-2008 truck, I would strongly suggest sticking with what was originally specified for it (which would be Mercon, a.k.a. Dex/Merc).

Thank you for this fantastically informative information. I had no other source of information so complete as what you are stating here. For many of us, we are often just shooting in the dark.

 

[JohnnyO]

The confusion comes from a 2007 directive from Ford that claims Mercon V fluid is backward-compatible in applications calling for Mercon fluid. While Mercon V does seem to be OK in automatic transmissions that originally called for Mercon (such as the A4LD), this hasn't been the case with the manuals. There have been a multitude of reports (and I have witnessed this myself) of hard shifting occurring on M5OD transmissions after changing the fluid to Mercon V.

This is very likely why Mercon fluid continues to exists in the aftermarket as "Dex/Merc" and other brandings such as "Multi-Vehicle ATF" (this because Ford at the same time also decided to yank the license to sell the fluid under the "Mercon" trademark).


Since you have a 2010, there shouldn't be confusion (Ford actually made the recommendation for Mercon V for yours).
However with a pre-2008 truck, I would strongly suggest sticking with what was originally specified for it (which would be Mercon, a.k.a. Dex/Merc).

Apples and oranges maybe, but I always thought it was strange that my old 2008 Sport Trac called for Mercon V in the transmission but Mercon IV in the transfer case.

 

[Eddo Rogue]

The best fluid for your transmission is the fluid recommended in your owner's manual.





Ask a stupid question, get a stupid answer.

That was not a stupid answer, just a little abstract...
Do you mean service manual (like a clymer or haynes) or owners manual? (like the one in the dash)?
I did not think the latter would provide such a specification.

 

[Eddo Rogue]

We used to call the fluid Mercon III but that wasn't right- it was Mercon/Dexron III, if we called our Motorcraft supplier and asked for Mercon III they'd send us the right stuff so I guess we weren't alone in calling it that. Type F isn't as slippery so the syncros might not work right, maybe a little balky about shifting. Motorcraft doesn't sell Mercon/Dexron III anymore but Napa does so I get it from them. If you put synthetic fluid in a T5 it won't shift right- the blocker rings slip too much but I don't know about the M5OD.
I won't buy Pennzoil at any price, they own Jiffy Lube and the concept of Jiffy Lube wouldn't occur to anyone if technicians got 1/10th the respect they deserve. I don't care if the product is any good or not.

My Fusion was borrowed once and taken to a jiffy lube, under false assumption I was being done a favor. Hasn't ran right since.

They don't drain the oil anymore, too many stripped/ wrong drain bolts. They just pump it out through the dipstick tube now. Sketchy.

Edit: I mean this is how they do the engine oil changes.

 

[Garth Libre]

Thanks to all, especially to 4x4Junkie who mentioned that later model M5OD transmissions (as is my 2010) do well on Mercon V. I just changed the tranny fluid this afternoon at 30,000 miles with Napa Mercon V. The magnetic plug showed nearly zero metal particles (120,000 plus miles) from my previous Mercon V change and I experience no hard shifting. While I was under the truck and dirty, I did an oil change with Motorcraft oil and filter at 3,500 miles. I'm as slow as molasses in all my car work but the two fluid changes only took me a shade over an hour including clean up and shower and cleaning the garage floor and packaging the used oil up for recycling. It feels like I'm slow but maybe that's the speed a 68 year old man can be expected to achieve. The satisfaction of taking care of these jobs myself far exceeds the amount of money it costs me.

Total expense :
5 qt. container of Motorcraft Semi Synthetic oil $37
Motorcraft oil filter $4
3 QTS Napa Mercon V $34.50

Total : $75.50 for engine oil change and tranny oil change.

I'm sure I could go to Jiffy Lube and only spend a little more but I don't trust them. My local garage would charge maybe $150 for both but I still feel I should be doing it.

 

[Garth Libre]

Thanks to all, especially to 4x4Junkie who mentioned that later model M5OD transmissions (as is my 2010) do well on Mercon V. I just changed the tranny fluid this afternoon with 30,000 miles since the last change with Napa Mercon V. The magnetic plug showed nearly zero metal particles (120,000 plus miles on the odometer). I experience no hard shifting. While I was under the truck and dirty, I did an oil change with Motorcraft oil and filter at 3,500 miles. I'm as slow as molasses in all my car work but the two fluid changes only took me a shade over an hour including clean up and shower and cleaning the garage floor and packaging the used oil up for recycling. It feels like I'm slow but maybe that's the speed a 68 year old man can be expected to achieve. The satisfaction of taking care of these jobs myself far exceeds the amount of money it saves me.

Total expense :
5 qt. container of Motorcraft Semi Synthetic oil $37
Motorcraft oil filter $4
3 QTS Napa Mercon V $34.50

Total : $75.50 for engine oil change and tranny oil change.

I'm sure I could go to Jiffy Lube and only spend a little more but I don't trust them. My local garage would charge maybe $150 for both but I still feel I should be doing it.

 

[Garth Libre]

Here she is serviced and ready for more action

 

[Garth Libre]

By the way, for shits and giggles, I called Jiffy Lube and asked what they charge for a manual transmission oil change on a Ranger and they said and I kid you not..."We don't do manual transmission fluid changes on cars with over 100,000 miles." WTF?

 

[Roert42]

Did you tell them your truck only has 10k miles?
Lol