Hi,

Could someone help me out. I just "accidentally" drained 4 qts of transmission fluid from my 99 F250 V10 Superduty 4X4 truck with AT(I bought it used, so I don't know what might have been put in the tranny). When I went to my friendly auto parts center and asked what kind of fluid to buy, they said Ford had gone to synthetic Mercon V since 96 or something. So I put in the 4 qts. of Mercon V.
However, the dipstick states Mercon, the manual states Mercon and also states never mix Mercon and Mercon V.
Was I wrong to put in the Mercon V? Do I need to drain the tranny completely and start over? If I do which oil do I use?
Thanks, confused.

 

It most likely won't hurt anything,but if it makes you feel better,get the trans flushed,
or change it your self. Drop the pan,change the filter,and drain the converter to make
sure you get all the old fluid out. It will take about 16-17 qts to refill the trans,and only put 6-7 qts in,start the engine to refill the converter,then put the rest in while
the engine is running. I am a auto tech and do these services regularly. I once put
Mercon V in my brother in laws escort during a trans flush because I thought all ford
cars built after 97,all used it. He drove the car this way for 60,000 more miles after
the service,sold the car and as far as I know the car is still being drien! Always
check the dipstick,this 99 escort was supossed to have Mercon! I did'nt even know
I put in the wrong fluid until well after the service!

 

One difference between the V and the regular Mercon is that a newer ATF contains some additive that is not compatible with some older seals. Since you had it diluted quite a bit, I wouldn't worry and wait for the next scheduked ATF change.

 

MERCON and MERCON V are not the same and are not interchangeable in the 4R100. Ford has a TSB out on this, and even puts a warning in the owners manual.

That being said, the 4R100 holds 18 qts. MERCON and MERCON V are not so different that a 4/18 ratio is going to do much (if any) harm until your next fluid change.

 

Thanks for your helpful remarks. I still wonder why they put Mercon it the 4R100 when they had gone syn. in their other vehicles.

 

I am about to change my ATF in my truck upon reading the back of the MERCON V bottle it reads the following. "Approved for use in vehicles that specify Ford Mercon, Ford Mercon V, Dexron III, Dexron IIE, or Dexron ATF. I am not sure but that seems to indicate they are interchangable.

 

The oil companies say that they are interchangeable. Ford says they may cause damage if you use MERCON V where MERCON is specified. You have to pick who to believe. I believe Ford knows what these trannys need better than the oil companies do.

And MERCON V is not a full synthetic. The factory fill is a synthetic blend.

As for the original question, I'd change all the fluid ASAP. There is a good article on how to do it in the Tech Articles at FTE.

 

That is true, and I believe that Mercon V also has additional friction modifiers in it, and is in essence a "slippier" fluid, which of course is fine for those tranny's that are designed for it, but not so good for the trannies that aren't.