'98 BW4405 TC correct fluid - MercV or Merc/DexIII??

[bryansr]

I know there are plenty of threads here about which fluid replaces the straight "Mercon" spec'd for my Explorer, but I can't derive a definite answer from any of them. I even called 2 local Ford dealers, one says to use MercV and the other says Merc/DexIII. Thoroughly confused, I tried searching for an actual Ford announcement on what to use, and I find a site calling for an actual "Transfer Case Fluid" which neither dealer even mentioned... I'm really lost now..... Any suggestions or does anyone know of a formal announcement from Ford on what replaces Mercon in a '98 transfer case??

 

[koda2000]

Universal Dexron III/Mercon is fine. You're not going to find Mercon anymore and Mercon V is not needed.

 

[drdoom]

Yes the DEX/Merc is what you want. Or Mobil1 synthetic is fine as well.

 

[pcam13]

I used dex 3

 

[joecrna]

Ford Transfer case fluid is what I use. Its the same stuff as the old Mercon. If I were to use something at the parts store it would be Merc/Dex III. I would only use MerconV if I had too. Each have slightly different frictional coefficients (obviously not by much) but it is how manufactureers fine tune transmission shift characteristics.

 

[PAExplorerXLT]

Yes the DEX/Merc is what you want. Or Mobil1 synthetic is fine as well.

You can use motor oil in the transmission?

 

[joecrna]

Transmission fluid in the transfer case.

 

[koda2000]

you can use motor oil in the transmission?

no!

 

[masospaghetti]

I don't think it matters (Mercon V vs Dex/Merc). The viscosity is the main thing to be concerned with. Unlike a transmission, the additive package and friction modifiers aren't very important - the fluid is really only used for lubrication in the transfer case, not as a hydraulic fluid + lubricant + coolant.

I wouldn't do it personally, but I bet a 0w-20 motor oil (which is similar viscosity to ATF) would work just fine in the transfer case.

 

[koda2000]

I don't think it matters (Mercon V vs Dex/Merc). The viscosity is the main thing to be concerned with. Unlike a transmission, the additive package and friction modifiers aren't very important - the fluid is really only used for lubrication in the transfer case, not as a hydraulic fluid + lubricant + coolant.

I wouldn't do it personally, but I bet a 0w-20 motor oil (which is similar viscosity to ATF) would work just fine in the transfer case.

Dex III/Mercon or Mercon V will work fine. Mercon V is not required and more expensive, so why use it, unless you have it lying around. I would strongly suggest against using motor oil in the t-case (maybe it would work ok but why risk it).

 

[masospaghetti]

You're right, Mercon V is probably unnecessary in the TC, but it IS a better ATF and it might last longer and/or tolerate high-stress conditions better.

It might be overkill, but it's also only a couple extra dollars since the TC only needs a couple quarts anyway.

 

[drdoom]

No, Mobil1 ATF is OK. I would not use MercV due to the clutch pack. Really the DEX/Merc is fine and correct. That case is known to be hard on the fluid, so main thing is change it fairly often.

 

[SoNic67]

There is no clutch pack inside BW4404.
The owner manual (who reads that anymore?) requires Mercon, but MerconV is an improved version, with a TSB that it can be substituted everywhere in place of Mercon.
I used MerconV mainly because I didn't trust the Mercon/Dex generic one.

 

[masospaghetti]

it's a BW4405, not a BW4404.

But still, I doubt that one clutch pack is going to care if Mercon V or Dex/Merc is used. If anything, Mercon V will last longer before it shears or loses its additive pack.

 

[SoNic67]

Ah, I am blind I guess... I saw 98 Eddie Bauer in his vehicle specs and I assumed V8 EB.
But yes, I agree that Ford used Mercon inside there because... there was no reason to develop another fluid. Is not a critical item for a TC, as it is inside of a transmission.

 

[drdoom]

OK so either will work, but the MercV is best? EDIT: NO! Dex/Merc or preferably Motorcraft XL-12 transfer case fluid. Do not substitute with MercV.