Hey guys need a little help need some ATF for my 92 XJ Auto and it seems everywhere I look online people say DEX III is what the aw4 want but every parts store only has DEX VI and even thought on the bottle it says" works for GM DEX II, DEX III, AND DEX VI applications " will this still be OK in my XJ without causing major issues?

 

From everything I've read it's fine as long as it lists compatibility with Dex III. Motorcraft Dex V may not be safe. Trans fluid is a complex oil and it can have a lot of differing characteristics. I used a mix of Dex V and Amsoil Universal when I did mine and felt no change.

 

Ya this bottle said nothing about dex v just 2 3 and 6 and if u say dex 5 is no good why did you put it in your jeep?

 

There is no such thing as Dexron V. It is Mercon V and it is a Ford only fluid.


Mercon III and Dexron III are equivalent and often sold as the same container. Merc-Dex III or MD-3.


I know many of the Dexron VI fluids claim to be Dexron III compatible and are probably fine, but if it were me I would keep looking for some Dexron III.

 

Only the Motorcraft branded V is a potential problem, tho not confirmed, and I didn't use it.

 

Ahhh OK so dex3 only and if I can't find it dex/merc3 ?

 

I use Valvoline Maxlife Dex/Merc in my 87. Shifts great.

 

From what I've read Dex/Merc is exactly the same as DexIII, they've just changed the labeling. The newer stuff is synthetic so it may have some benefits and many people have put many miles on the synthetics in the AX4 with good results.

 

Sorry for my screwup and thanks for catching it, yes I meant Merc V not Dex V. From what I've read the non Motorcraft V is backwards compatible but the Motorcraft branded one isn't. Tho it seems illogical I think it comes down to other fluids meeting minimum requirements to wear the Merc V badge vs. being made to an exact spec., or it may just be a labeling thing.

 

Merc/Dex III and DEX III same stuff.


I did a bit more research (Google is your friend) and Dex VI is basically the same as Dex III but with a lower viscosity to help reduce drag and increase fractional mileage gains.


As for Mercon V, it is a different animal and from what I've read has different friction coefficents than Dexron types. Shouldn't matter much if it is Motorcraft branded or not it still needs to meet the specifications to be branded as such (FYI, somebody else makes it for Motorcraft). What that means is the clutch packs in your trans are either engaging too fast - or too slow - depending on the friction properties of the fluid, compared to the correct Dex/Merc III fluid. Either way it will shorten their life to some degree even though it may "feel OK".