All right, I'm ready to get dirty again and I want to change the differential fluid because it's time and I'm getting some strange noises in the back on slow tight turns. It's a 92 Fac posi. I drive mostly freeways. Q's are. What is the preferred brand and weight gear oil to use? Reg or Synth? Are any of the other brand posi additive's any good or just stick with GM? Can you get the new oil in using the bottle with the nozzle on top or do I need a small hand pump? What brand is the preferred cover gasket? I'd just like to get the right stuff the first time for a change, Thanks.

 

I'm using the Redline 80W140 (#58104, $7.95/qt from Summit). Posi additive's already in it.
You'll need some kind of pump to put it in.
Factory's not using gaskets any more, just Sealant (silicone), so that's been working fine for me.
-Rich-

 

i use fel pro gaskets, moble 1 or amsoil synthetic gear oil, and gm posi additive, reguardless of what the oil maker says.

 

I use the Mobil 1 gear oil.