Gear lube for front/rear diffs, Please help

[EXMR2]

Ive got a 92 Explorer W/ 3.73 gears and Traction Lok limitied slip rear, all stock. I want to change the fluid in both diffs, now a did a search on the subject and came up with several different answeres, one saying that Ford has revised it and the rear get 75/140w full synthetic???. My owners manual says 80/90w for the rear W/ 4oz. of friction modifier, and in the front 75/140w full synthetic, which is what I'd do except that the only place I can find 75/140 synthetic is @ Ford for $17/quart!!! Can anyone shed some light on this subject, What I was thinking of doing is that I did find 75/90w full sythetic and 85/140w full synthetic, I was thinking of mixing the 2 together for the front diff and using the 80/90w W/ friction modifier for the rear, does this sound ok to do? if not, what should I do?

 

[Hotweels]

I have the same axels you do, i used 80/90w full synthetic in the front just look at the manual it will give a oil spec like api80hpgo (bad example) then look at the specs on the oil bottle and it will say "replaces api8hpgo" as for the back diff just use what it says to in the manual.

 

[Alec]

I use the expensive motorcraft stuff with the friction modifier. I figure I only have to change the fluid if I get water in it or to service the gears or posi. Just that way I'm sure I have the right stuff in there.

 

[DesertSpive]

My 8.8" with the Torsen ('02 FX4) comes from the factory with Ford synthetic 75w-140. My dealer stocks it. The only other company I could find making the 75w-140, is Amsoil. I used it when I replaced my diff cover. Amsoil also formulates their synthetic so that you do not have to use a friction modifier, although it is compatible with a friction modifier if you want to use it. You can buy it direct for about $12.05/qt. www.amsoil.com

--Sean

 

[Fred Garvin]

I have 4-5 qts of the Motorcraft 75W140 full syn rear lube. I bought a full 12 qt case last Sept. when I changed my lube. The quarts are still sealed.
I can send it for $12 per qt, postpaid. The friction modifier is available from Ford for about $4 a 4 oz. bottle.
email before May 2nd:drewshiers@hotmail.com

 

[biggs85]

Sorry to bring this thread back up but I was also wondering the same thing for my 91' explorer. I've seen from everyone that from at least 95' and up the 75w140 oil is what's used for the rear axle. In my owners manual it gives the ford part numbers. I looked them up on the Autozone web site specifications and it says that only the front requires 75w140 and the rear requires (90w). It only says 90w with the friction modifier for l/s. Everyone has been saying different things. I see that Ford has changed the specs for the rear axle of 95' and up to 75w140 but what about 91'-94'? Then I see that the front differentials require 75 or 80w90 for the front of 95' and up explorers. Should I still use 75w140 for the front like the Autozone site says for my 91'. And am I supposed to use 75w140 for the rear also when it says 90w? I've never even hear of just 90w and I don't really trust Autozone anyway.

 

[mjbach]

We went to the Ford dealer for the correct fluid for our 97 XLT with limited slip differential. They had us look for a tag/label on the differential itself which said it wanted synthetic, 75w140 rear differential lube. We added two bottles of the conditioner for clutch packs in the limited slip differential.

This was an issue for us because the limited slip was no longer slipping and causing loud noises on dry pavement when making tight turns. The two bottles fixed the problem.

I believe the owners manual gave us incorrect/incomplete information regarding the fluids.

Also, replaced the gasket/seal on the rear differential which was not available through Ford. Bought at Autozone.

 

[biggs85]

I guess I'll have to go to the Ford dealer to find out. Would it hurt to just put the 75w140 in the front and rear?

 

[mjbach]

My husband changed the front differential fluid also just as a precaution for my daughter's vehicle. As I recall, he used transmission fluid. If you're going to Ford anyway for the rear differential fluids/clutch slip additive, you might as well ask them about the front fluid.

Regarding the seal change on the rear differential, there was some evidence of a slow leak around the bottom of the cover. The cover was only sealed with the black silicon stuff and that's what the manual recommended. He added the gasket in there for a better seal but still used the silicon stuff with the gasket. I don't recall if he had to buy a new gasket for the front.

When you're down there, you might also look for evidence of leakage at the pinion seal which is located on the front part of the rear differential. The dealer had pointed that out that leak and we replaced it too.

Something else that I read here that's easy to do is lube the slip yoke.