Mercon III used on Ford Ranger Manual Trans Today- Mistake??

[btcman]

Today I had the transmission fluid changed on my 1998 Ford Ranger with manual transmission with 115,000 miles. I asked the mechanic to use Mercon III instead of Mercon V as was recommended. I told him I thought that synthetic fluid could cause the transmission to slip on my truck with its high mileage. The fluid was changed last in 2008 at 92,000 miles and it was quite black, but not much sludge and metal flakes on the plug.
My question is should I have the fluid changed immediately to Mercon V. I have been reading posts on several Ford forums that indicated Mercon V was best for a manual transmission, including one post that included a service bulletin from Ford in 2007 that recommended using Mercon V fluid. I just spent $87 to change the fluid, and would like to change to Mercon V at next change (maybe in 10,000 miles which may be a good bit in future since I do not drive the truck much). However, if the consensus is that Mercon V would be much better for the performance and longevity of my transmission, then I would change the fluid.

 

[koda2000]

Mercon III has been superseded by Mercon V (the current Ford spec). I don't see where you've said what the mechanic actually put in. Mercon III is no longer available. About the closest you can get to Mercon III would be Dex/Merc. Personally I'd have gone with what Ford is currently recommending, which is Mercon V.

Question: You say you have a manual transmission. How does a manual transmission slip?

In any event, if the fluid has already been changed, I wouldn't be too concerned about it.

 

[CDW6212R]

Yes, with a manual transmission it's more about the shift feel, not any wear created by a certain fluid. It's really important in an automatic, but not in your manual. Wait until the next time to change to the current recommended fluid, you're fine.

BTW, the last Ford spec before Mercon V was Mercon(or Mercon I). The last fluid was commonly bought as both Dexron III, and as the Mercon I ATF, labeled Mercon/Dexron III.
The Mercon is no longer available, but makers still label their old fluid the same way, so it is available. Funny logic yes.

 

[btcman]

Mercon III has been superseded by Mercon V (the current Ford spec). I don't see where you've said what the mechanic actually put in. Mercon III is no longer available. About the closest you can get to Mercon III would be Dex/Merc. Personally I'd have gone with what Ford is currently recommending, which is Mercon V.

Question: You say you have a manual transmission. How does a manual transmission slip?

In any event, if the fluid has already been changed, I wouldn't be too concerned about it.

Thanks for your reply. I wish I had done my homework about correct fluid to use before making the mistake. I got mixed up about the cautions about replacing regular oil with synthetic when changing oil in high mileage cars - for my other automatic transmission cars, like my 1996 Maxima with 269,000 miles. Also, I thought that the mechanic was trying to upsell me in recommending Mercon V instead of III. I wished he had pushed back when I told him I was concerned about changing to synthetic due to chance of transmission slipping, just like you did. My son drove the truck when the last fluid change was done in 2008 and I am not sure which fluid was used then. What potential problems should I be looking for now that I have the wrong fluid in the transmission?

 

[koda2000]

I don't think you'll have any problems with whatever ATF the put in your manual trans. I won't worry about it. The next time you change it put in Mercon V.

 

[btcman]

Yes, with a manual transmission it's more about the shift feel, not any wear created by a certain fluid. It's really important in an automatic, but not in your manual. Wait until the next time to change to the current recommended fluid, you're fine.

BTW, the last Ford spec before Mercon V was Mercon(or Mercon I). The last fluid was commonly bought as both Dexron III, and as the Mercon I ATF, labeled Mercon/Dexron III.
The Mercon is no longer available, but makers still label their old fluid the same way, so it is available. Funny logic yes.

 

[btcman]

I mistakenly advised that the transmission fluid in my manual transmission was replaced with Mercon III ATF. Actually it was "Proline Dextron III & Other Mercon Brands" ATF, as you pointed out is now available in addition to Mercon V. You advised to switch to Mercon V on next change. In the meantime, is there any change in how my transmission may perform that I should be looking for? By the way, I also probably should have required that a better known brand of ATF be used as well.

 

[RangerX]

Different ATFs may be crucial in an auto trans, but I would think all that matters to the manual trans is the viscosity, which should be pretty similar across the range of ATF products. I've seen posts where people have poured in gear oil, talk about thick!
I think it'll be fine. For peace of mind, if you don't want to spend another $87 to have it changed, it's very easy to do yourself, there's a drain plug and a fill plug right there on the side of trans.

 

[rb142]

Do not change it. Regular Merc is what is supposed to be in there, and it works better in that transmission than Merc V. The only reason Ford changed the recommendation is because they don't have regular Merc anymore, so they had to change it to something they had. Dex/Merc has better shift feel in the older manuals. You aren't going to do any damage either way though.

 

[CDW6212R]

Do not change it. Regular Merc is what is supposed to be in there, and it works better in that transmission than Merc V. The only reason Ford changed the recommendation is because they don't have regular Merc anymore, so they had to change it to something they had. Dex/Merc has better shift feel in the older manuals. You aren't going to do any damage either way though.

Agreed. Ford ended the rights to make Mercon a few years ago, and they want to sell people a fluid they do carry. They sure wouldn't want to be recommending that people go to other sources and buy Dexron III, simply because it's made to meet the obsolete Mercon standard. That would look bad.