Mercon V replace Mercon in all applications?

[duffmanrha]

I have a '99 Cobra with the T-45 manual trans, and it uses regular Dexron III/Mercon ATF, and I would prefer to use Motorcraft but all I can find is Mercon V. I have read various forums while searching this, and some people have been using Mercon V fluid in their Dexron III/Mercon-specified transmissions. Does Mercon V supercede Mercon in all applications or is it different enough that Mercon should SPECIFICALLY and only used?

 

[bdcardinal]

Yes it has. The only exception being transfer cases which now specifically spec Motorcraft Transfer Case Fluid as opposed to Mercon V.

 

[Bgallagher]

Yes, MV replaced mercon similar to how dex VI replaces dex. I made the switch to maxlife for all my dex/merc and merc V applications. Seems to do a really good job. Considering the car is a few years older it would be great for your application

 

[bdcardinal]

Be very careful calling it MV, as opposed to Mercon V. Mazda has a trans fluid they call M-V or M5 that Ford calls FNR5 fluid that is not compatible with Mercon V. One of the dealers here is waiting on a new trans after putting Mercon V into a car that called for MV and the trans slips like crazy.

 

[mechtech2]

Duff -

MerconV was specifically prohibited in Mercon applications by Ford.
Then, magically, it was OK'd. Probably always was OK.

I would look into an aftermarket dedicated real manual trans fluid from Redline or Amsoil.
If you have carbon fiber synchros, ATF is probably best [but some have had great success with manual trans lubes].
If you have brass, I'd ditch the ATF for sure.

 

[duffmanrha]

I like using Motorcraft but no one around here sells the stuff, except for the dealer of course. I used Valvoline maxlife in my old 5.0 which was also a manual shift and it seemed to work well. From what I have read, non-synthetic or at most a synthetic blend is recommended for manual transmissions that use Dex/Merc fluid - something to do with the brass shift forks and/or synchros?

mechtech2 - I am assuming I have brass shift forks, so you are saying to ditch the ATF meaning to NOT use Mercon V, or what?

Thanks for all the help so far, really appreciate it!

 

[duffmanrha]

Also, while on the topic, if I don't need a non-synthetic, what would everyone recommend? I've read and heard good things on Redline and Mobil 1 but wanted to get more opinions.

Also, I see that Redline sells a D4 and D6 fluids - both satisfy Dex III/Mercon and that D6 is lower viscosity for fuel effeciency (per Redline's website) so which one is better?

 

[Rand]

mercon V had issues with older seals like the ones in 1994 ford thunderbirds.. when mercon V first came out.

it may have been reformulated or they just dont mention that any more.

I'm pretty sure anything 1997 and later is fully compatible.

 

[WMSmotorhead]

MerconV is pretty easy to come by... Most "Muti-Vehicle" ATF's meet the spec. I don't usually freak out about trans fluid, provided the stuff is Marked on the bottle as "Good for X-application" and it's made by a company that has a track record of meeting all the specs their bottle says they meet.

 

[mechtech2]

Duff - It's the actual synchros that are brass or carbon fiber faced. The shift forks are cast iron or steel.
The carbon fiber variety likes ATF, at the expense of ATFs lower performance for the other trans parts.