What oil in Transfer case and Front differential?

[Billy V]

I'm about to use this 4x4 for its intended purpose....lol

Which oils are you running in the Transfer case and Differentials?

Do I need to use the GM additive in the Front differential?

Thanks in advance

[rapidoxidationman]

If your wallet lets you, put synthetic gear oil in the front differential (80W90) and I'm not sure about your t-case, but mine takes dexron 3 ATF.
If you submarine your truck past the axles it's a good idea to change the fluids or at least check them for water.
Have Fun!
Rapid

[DmaxMaverick]

If your truck is OEM/stock....

Front diff. uses 80w-90 (GL-5, not GL-4) gear oil. Synthetic is better, use 75w-90.

Transfer case uses Dexron III (or Dexron IV, now). Same stuff that goes in the auto tranny.

Unless you have upgraded the front to limited slip, the additive is not needed. I don't think the front locker/limited slip was an option for '93. If you (or someone else) have upgraded the front diff. to an aftermarket unit, check with the original Mfgr.

Check the RPO code for the rear end, also. If it is G80, then the additive is needed there. If it has an aftermarket limited slip or locker, check with the manufacturer. Some need it, some not. It is not recommended to use the additive if not needed.

If you are sure all the gears are original, check the options list in the glove box. There is an RPO code reference in the reference section here:

RPO codes (http://www.thedieselpage.com/members/rpocodes.htm)

Cheers