Is Dextron III with a Mercon friction modifier ok in the 4R70W tranny? I've seen Dextron III/Mercon labeld together on the same container.

 

First off you really need to be running Mercon V in your tranny unless it's pre '98 vintage. As far as additives, can't say. Wy bother. There are plenty of Mercon V fluids out there.

 

I agree. A local tranny guy said that is what he puts in the transmisions he services?? I changed the fluid myself and put in Mercon V.

 

Mercon V is the fluid of choice in ANY 4r70w transmission.

Period.

 

JustinH
It wasn't until late 97 early 98 that Ford started putting Mercon V in the trannys. Look on the trans dip stick, it should tell you to use Mercon or Mercon V.
When I changed mine about 6K ago, I put in Castrol Mercon/Dextron III, and no problems.

 

Adding a friction moidifier to MERCON makes it MERCON V, most tranny shops just stock one kind of fluid, and if they need MERCON V they add the modifier. Any 4R70W can be refilled with MERCON V, although they originally came with MERCON, but don't put any modifier in a 4R100, it only takes MERCON, never MERCON V.

Hope this helps,

G

 

Yes you are right the earlier 4r70w's came with mercon V from the factory.

There is a ford TSB out that recommends Mercon V in all 4r70w's for torque converter shudder.

Regards,
Justin

 

What does the Ford dealers put in?

I talked to a number of places around town and they all used the mercon fluid with a modifier. That's not what I wanted, so I went to ford.

None would put synthetic in. If I wanted to use synthetic I had to argue just to be able to buy my own fluid and pay half price for the change using the fluid I supplied.

I expected that Ford was using a Mercon V fluid.