Questions about transfer case and rear end fuild

[kdoggy]

OK!

First off, I picked up Mobile 1 75W-90 for my transfer case. This is the right stuff, I mean it will work right? Weight wise and such. Do I need any additives?

Then for the rear end I wasn't sure what to get. I was told I might need 75W-140 with a friction modifier, how do I know for sure though? How do I tell if I have an LS rear end. I plan to use Mobile 1 here too.

Also I noticed that the Mobile 1 stuff has the letters LS on the bottle, does this have anything to do with anything or just a coincidence?

Thanks!

 

[irocdupi]

Hold On. The transfer case takes automatic transmission fluid. Not gear oil

 

[mpntball2012]

What iroc said, the t-case takes ATF not gear oil. about 1.9 quarts worth (I think, somebody correct me if I'm wrong.)
Easy way to tell about your rear end is to look at the ID sticker by the latch of the driver door. Then go here and match the code: http://www.explorerforum.com/forums/showthread.php?t=239360

Or I believed there's a tag on the differential itself that has the codes.

 

[jrford]

as they all said, . .
Mobile 1 75W-90 - use in Front Diff, used 1.5 bottles.
Mobile 1 75W-140 - use in Rear Diff, used 1.5 bottles, if you do have LSD rear, i'd toss in 4 oz of the Ford Friction Modifier, i'd use OEM.

Now i've hear rebuilders using only the 75w-140 just so they don't have to use two weights or types of oil, but its required in the rear for sure.


Xfr Case i forgot what i used ATF something, Mobile 1 ATF would work, i think i used a Mercon though, not sure.

 

[esclamada]

In my case, royal purple for Transfer Case and Mobil 1 75w140 for rear diff. Haven't changed my front diff (use 75w90)

http://www.facebook.com/album.php?id=110528882348605&aid=21032

 

[kdoggy]

Well, you don't say. Hmm, my last two cars used gear oil for the transfer cases and the rear ends.

Glad I asked.

I think I have some cheap Mercon ATF in the garage from my last Ford car, unopened new bottles though.

 

[04 EDGE]

Ford has not used gear oil in their Tcases sense the 70's!

 

[imp]

Gear Oil vs. ATF

I think the reason for changing to ATF from the old gear lube was mostly for less fuel wasted "churning" the stuff in there. Evidently, the newer ATF lubricants are capable of maintaining a film of lube between gear teeth much better than the old stuff. I used ATF in my stick shifts backs in the 60s; my friends said I was nuts, but never ate any gears.

The old hypoid gear lubricants, like 90W, 140W, etc., got thick as hell when cold and took a LOT of power to just move the lubricant around. Even hot 140W is still pretty thick yet.

I suspect using gear oil in today's transfer cases MIGHT not hurt any, from a mechanical durability standpoint, but it'a a loaded question whether the additives might or might not affect electronic clutch linings, seals, and so on. Hypoid gear lubes contain lots of sulfur compounds; that's what makes them STINK so bad. Back in the day, only leather could withstand gear oil, until better "man-made" rubber compounds were developed. The earliest of those, Buna-N, was "eaten" by gear lubes. A later development, Poly-acrylic, worked quite well; so does "Viton", which is a filled-teflon material. Silicone was a failure with gear lube early-on.

My guess is, that Mercon-V seems pretty nasty compared to the old petroleum-based ATFs, so today's seals, being able to handle it, proly could work well with gear lube. But, NOT POSITIVE. imp