First transfer case & differential

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351mustang65

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I have a 04 Mountaineer premier V8 AWD with about 110k on it and I would like to change the fluid in both the transfer case and differential. I have never done this before and was wondering if you guys had any recommendations on fluids.

I was thinking of going with Amsoil 75w90 Severe Gear or Long Life Synthetic Gear Lube & Slip Lock Gear Oil Additive for the rear diff but am not sure if I can find it locally or not. for the front I am really not sure what ATF to go with. Or should I just use the same stuff I put in the rear?
 
According to the owner's manual which can be found here. The rear differential uses Motorcraft SAE 75W-90 Fuel Efficient High Performance Synthetic Rear Axle Lubricant and the transfer case uses Motorcraft MERCON ATF. The front differential uses Motorcraft SAE 80W-90 Premium Rear Axle Lubricant.

I would contact Pablo and probably go with the Amsoil 75W-90 Synthetic Long Life Gear Lube in both axles (unless he had another recommendation). I would stick with Ford Mercon ATF in the transfer case (it has served you well for 110K thus far and I use Ford brand in my FX4 transfer case and has given me good UOAs both times).
 
Originally Posted By: MolaKule
Rear diffy requires a 75W140.

Front diffy requires a 75W90.

For both diffy's, I would use a 75W110 such as LE's http://www.le-international.com/uploads/documents/1605.pdf

Transfer case requires an ATF. Recommend TorqueDrive or Transynd.


As 2010_FX4 said my manual calls for front 80w90 rear 75w90 and I was just going to go with 75w90 for both.
 
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There must have been a mid-year change on the specs.

Pablo can probably fix you up with what you need so send a PM to him.
 
Any GL-5 lube in 75w-90 will do a fine job and easily return another 100k+ miles. Any lube that meets J2360 is going to be even "better" (there is a long list of approved fluids that meet this more-demanding spec, and several of them are not even syns!).

As for the t-case, it calls for Mercon ATF so any (formerly conceived Dex/Merc) fluid will work, but you'll get much longer service, and likely better evaporation and oxidation resistance, from any synthetic ATF that is intended for the Dex/Merc applications. (I would exclude LV and DEX VI from this; a bit thin). Products such as Mobil 1 ATF would work, as well as many of the Amsoil products like ATF and ATD, as well as the other "clones" of ATF and TES-295 type products.

I'll also note that at 110k miles, it's likely that your rear diff, if equipped with the Ford Traction-Lok torque balance equipment, is probably really weak by now as it's had plenty of wear on the clutches. Don't be surprised if there is a lot of material in the fluid you drain, and it does not seem the "same" when the new fluid is added.
 
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Factory spec on my mountaineer premier awd is 75w140 syn in rear axle, 80w90 front. Mercon in tcase.
 
Originally Posted By: 95busa
Factory spec on my mountaineer premier awd is 75w140 syn in rear axle, 80w90 front. Mercon in tcase.

2004 vs. 2007? His OM states 75w-90 and 80w-90.
 
Ford changed the spec in later years as they did on most of their products to 75w-140. The question in my mind is "Is 75w-140 specced for better service life?" I suspect it is.
 
Originally Posted By: 95busa
Ford changed the spec in later years as they did on most of their products to 75w-140. The question in my mind is "Is 75w-140 specced for better service life?" I suspect it is.


My friend that works at a Ford dealership told me that they speced the 75W-140 to cover the gear whine in their rear diffs. I have said gear whine in my Mountaineer, and the 140 gear oil doesn't help the problem. It's been whiny since we bought it with 9k miles, and had never gotten worse or failed in any way, it's just noisy at 52-62 mph.

OP - any 75W-90 syn gear oil will work just find in the rear diff, and I used a store brand of Dex/Merc ATF to do the t-case recently. Regular 80W-90 for the front diff, too. No drain plug on the front diff, you have to suck the oil fluid out or remove the cover. Get yourself a 1/2 to 3/4 ratchet adapter if you don't have a 3/4 ratchet. You'll need it for the drain plug on the rear diff.
 
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Originally Posted By: dnewton3

I'll also note that at 110k miles, it's likely that your rear diff, if equipped with the Ford Traction-Lok torque balance equipment, is probably really weak by now as it's had plenty of wear on the clutches. Don't be surprised if there is a lot of material in the fluid you drain, and it does not seem the "same" when the new fluid is added.



What do you mean by not the same? This SUV has every option that I can think of so It probably has traction-lock as I am pretty sure most do but I have no noise at all from it when driving and when you put it on a lift there is very little play in it at all. The only problem I am having is the binding type noise on sharp turns form a stop sometimes (revers and forwards). I have been told that it could be the common rear clutch Chatter these things get and this might fix it.
 
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So are we saying 75w140 does not protect better than 75w90? I think the oems disagree, the ford lightning among other speccing 74w140 for durability reasons
 
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