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Mercon V appears to be super expensive everywhere these days, so I have a question:
1999 F-350 7.3 and 1999 F-53 V-10 motorhome, both with 4R100s. The F-53 is around 16,500 pounds empty and the F-350 is used for towing and hauling most of its miles, so both work for a living. I like to keep good fluids in them.
Unfortunately, the price of Mercon V has gone way up, availability has gone way down, and I need to do a service on the F-350. The owner's manual calls for Mercon ATF, but it has Mercon V in it. I've also seen notices everywhere (including the owner's manual) that the two fluids aren't compatible and never mix them together etc.
So . . . my choices are:
- Wait for prices to come down
- Pay an exorbitant price for name brand Mercon V
- Use a bargain brand Mercon V
- Switch to name brand Mercon ATF
I keep a close eye on fluids and maintenance either way, and I would expect to change bargain brand or Mercon ATF more often.
If it has a MERCON V rating, then Ford has tested it and it meets the MERCON V specification.
Originally Posted by CathedralCub
- Switch to name brand Mercon ATF
Where would you get MERCON? Ford stopped licensing MERCON in 2006. Nobody has made MERCON since then.
You can find DEX/MERC that says it is for use in transmissions that used MERCON or DEXRON. But nobody licences that fluid, so they can put ANYTHING in the bottle and call it DEX/MERC. Does it meet the now obsolete MERCON spec? Nobody knows. They could literally put straight 30 weight oil and there and call it DEX/MERC.
Mercon V appears to be super expensive everywhere these days, so I have a question:
1999 F-350 7.3 and 1999 F-53 V-10 motorhome, both with 4R100s. The F-53 is around 16,500 pounds empty and the F-350 is used for towing and hauling most of its miles, so both work for a living. I like to keep good fluids in them.
I'd ask how many miles on these transmissions and what is your normal mileage when you've done the full fluid exchange in the past?
You don't show your location but if you have Amazon delivery available I'd search for a known good quality brand Mercon V ATF there---I've done that to great success and do not use their "prime" scam.
At that current price it works out to about $8.60/qt.
I too would have a problem paying $15/qt however when comparing a replacement cost of the transmission it seems a rather paltry cost all things considered.
First time I did Mark K's flush the dealership beat NAPA and others price-per-quart by almost $2. I did buy 24 quarts but that quantity didn't affect the cost from any place I checked. Unfortunately my dealership of the time only sold AFT by the quart, wouldn't supply the 5 quart jugs as shown in the above Amazon link.
Do keep in mind I'm not budget restrained and tend to buy "the best" products keeping my Ford E-Series vans working---they're my source of income so simply don't spare the expense. I'm sure there are quite a few high quality AFT's suitable for Mercon V specified applications but Motorcraft is my go to brand as I'm very confident its up to the need. I'm not pulling heavy loads or running past my chassis rated GVWR but my 2002 E-350 does weigh about 8.400 #, the 4R75-E transmission in place. I also switched my full fluid exchange interval to 30K instead of the 50K I thought was recommended. Blackstone and a few others here suggested the internal change.
If it has a MERCON V rating, then Ford has tested it and it meets the MERCON V specification.
Good to know, but at the same time I want to use stuff that's as high quality as I can reasonably get. Mobil 1 Mercon V will hold up a lot better near the limits of the specification than some lesser brands that just barely meet the specification. Your example of the Baja transmissions with the melted solder is a good example. If I just drove an F-250 that is mostly used like a Buick and only occasionally carried some 2x4's then I wouldn't be worried about it so much. The F-350 mostly tows and hauls, and the F-53's 4R100 never ever sees easy service, except at idle in Park.
Originally Posted by CathedralCub
- Switch to name brand Mercon ATF
Originally Posted by Mark Kovalsky
Where would you get MERCON? Ford stopped licensing MERCON in 2006. Nobody has made MERCON since then.
Sorry, I was using the term "Mercon" too loosely. I was referring to the fluids that claim to be Mercon compatible like Supertech's "For use in Vehicles Previously Serviceable by DEXRON-III or MERCON Transmission Fluid". It doesn't say what it is certified and/or licensed as, just what the manufacturer intends it to be used for, which I'm sure their lawyers would claim is merely their opinion were I to have a provable issue.
Originally Posted by Mark Kovalsky
You can find DEX/MERC that says it is for use in transmissions that used MERCON or DEXRON. But nobody licenses that fluid, so they can put ANYTHING in the bottle and call it DEX/MERC. Does it meet the now obsolete MERCON spec? Nobody knows. They could literally put straight 30 weight oil and there and call it DEX/MERC.
I have used this for years on transmissions and transfer cases that call for Mercon, never had any problems.
I appreciate this, I'm just scared of the actual description "For use in Vehicles Previously Serviceable by DEXRON-III or MERCON Transmission Fluid". It doesn't say what it is certified and/or licensed as, just what the manufacturer intends it to be used for, which I'm sure their lawyers would claim is merely their opinion were I to have a provable issue.
If these were light duty I'd think differently.
Last edited by CathedralCub; Aug 2, 2025 at 06:45 PM.
Reason: Changed font from black to automatic for readability in dark mode
I appreciate this, I'm just scared of the actual description "For use in Vehicles Previously Serviceable by DEXRON-III or MERCON Transmission Fluid". It doesn't say what it is certified and/or licensed as, just what the manufacturer intends it to be used for, which I'm sure their lawyers would claim is merely their opinion were I to have a provable issue.
If these were light duty I'd think differently.
After over 10 years and hundreds of thousands of miles of use in multiple vehicles with out a single fluid related issue I am not too worried.
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