Mercon and Mercon V

Messages
472
Location
IL
Short and Sweet... Why aren't Mercon and Mercon V interchangeable? Ford says DO NOT mix the two together. For something like a PS application, would it really matter? I mean will there be some sort of chemical reaction that will blow up my PS pump if I mix them?
 
Messages
15,867
Location
NE,Ohio
IIRC back in the day if it spec'ed mercon and you used mercon V the seals werent compatible? there may have been other reasons. The specific application I'm thinking of is the 1994 Thunderbird. Mercon and Mercon V are different just like you wouldnt use Mercon V instead of Mercon LV etc.
 
Messages
3,897
Location
Canada
For PS, they are interchangeable as I've used both on my PS and it runs quiet and smooth. For the trans, I'd recommend only Mercon V, as after running regular Mercon it wasn't nearly as smooth shifting as it is with V. You can use Mercon, but I'd suggest using it as a flush as I did. If you get it at walmart, the Supertech version is fantastic and meets the same requirements as the other name brand Mercon V's, and is a bit cheaper.
 

lugNutz

Thread starter
Messages
472
Location
IL
Originally Posted By: Lolvoguy
For PS, they are interchangeable as I've used both on my PS and it runs quiet and smooth. For the trans, I'd recommend only Mercon V, as after running regular Mercon it wasn't nearly as smooth shifting as it is with V. You can use Mercon, but I'd suggest using it as a flush as I did. If you get it at walmart, the Supertech version is fantastic and meets the same requirements as the other name brand Mercon V's, and is a bit cheaper.
I too used the Supertech Mercon V in my trans and TC with no issues. But I put Mercon V in my PS resovoir, and it's fine, just curious why they basically say that it is a NO-NO.
 
Messages
12,925
Location
Northern Kentucky
Mercon V is superior with a synthetic blend oil composition compared to Mercon being mineral based. As far as the Ford TSB from 2006, Mercon V should be used in the place of Mercon but I wouldn't want to downgrade a Mercon V setup to mineral Mercon since it won't have as long of a service life or oxidation resistance. I am not sure about the exact change in friction modifiers but they are similar. FORD TSB #06-14-4
 
Messages
2,012
Location
.
The "do not mix" warning is an old one. On current Motorcraft Mercon V bottles it specifically says it is also for vehicles that originally specified Mercon. Now whether this applies to non-Motorcraft ATF, I don't know. But as Motorcraft is available at O'Reilly, it's easy to stick with it.
 

MolaKule

Staff member
Messages
21,908
Location
Iowegia - USA
Originally Posted By: 901Memphis
Mercon V is superior with a synthetic blend oil composition compared to Mercon being mineral based. As far as the Ford TSB from 2006, Mercon V should be used in the place of Mercon but I wouldn't want to downgrade a Mercon V setup to mineral Mercon since it won't have as long of a service life or oxidation resistance. I am not sure about the exact change in friction modifiers but they are similar. FORD TSB #06-14-4
I would have to agree. Essentially, Mercon V is simply a more stable version of Mercon. The Mercon V has better overall stability specs with the same 100C viscosity as Mercon. The base fluid mix and the PI package of Mercon V results in a more stable fluid in terms of friction modification, shear resistance, and VI. The friction coefficients of Mercon and Mercon V are very close.
 
Last edited:
Messages
14,732
Location
Central NY
Mercon in a transmission that requires Mercon V will cause torque converter shudder from what I have heard. I have mixed them in the PS pump and never had an issue.
 

MolaKule

Staff member
Messages
21,908
Location
Iowegia - USA
Originally Posted By: lugNutz
Short and Sweet... Why aren't Mercon and Mercon V interchangeable? Ford says DO NOT mix the two together. For something like a PS application, would it really matter? I mean will there be some sort of chemical reaction that will blow up my PS pump if I mix them?
The OP's topic was about Mercon fluids in PS systems. For a PS system, I think the more stable Mercon V would be better. I don't think mixing them in a PS system would cause a problem. If the OP is concerned about mixing, then drain and refill about 3 to four times with Mercon V to get rid of the oil Mercon.
 
Last edited:
Messages
17,301
Location
OH
For the PS, I doubt that it would matter. Our old Aerostar's PS pump was getting a little noisy after the first ten years or so and I noted that the resovoir was very low. Maybe it was sucking air? I topped it off with some generic PS fluid I had laying around and it was fine and quiet for the next 20K or so that we had beast. My point is that while the tranny might care, the power steering pump won't.
 

lugNutz

Thread starter
Messages
472
Location
IL
Originally Posted By: MolaKule
Originally Posted By: 901Memphis
Mercon V is superior with a synthetic blend oil composition compared to Mercon being mineral based. As far as the Ford TSB from 2006, Mercon V should be used in the place of Mercon but I wouldn't want to downgrade a Mercon V setup to mineral Mercon since it won't have as long of a service life or oxidation resistance. I am not sure about the exact change in friction modifiers but they are similar. FORD TSB #06-14-4
I would have to agree. Essentially, Mercon V is simply a more stable version of Mercon. The Mercon V has better overall stability specs with the same 100C viscosity as Mercon. The base fluid mix and the PI package of Mercon V results in a more stable fluid in terms of friction modification, shear resistance, and VI. The friction coefficients of Mercon and Mercon V are very close.
Thank you gentlemen!
 
Messages
8,598
Location
Florida
Originally Posted By: 901Memphis
The pump itself might not care, but seals might care if an entirely wrong fluid was used.
I understand that argument, but I have also encountered Fords that call for Type-F in the P/S pump. I'd either use regular Mercon, Mercon V, or a universal multivehicle ATF and never have a problem there either.
 
Top