The rearend on my '89 IROC is leaking pretty bad, so I got a new Felpro gasket and plan to replace it. The rearend is the 2.77 9-bolt Borg-Warner posi rearend. I've heard many times that on these particular rearends you're supposed to add an additive to the gear oil to keep them in good condition. I know that maintinence can be expensive on these rearends, so I want to do this right so that I never have to go down that road.

So, right now, this is what I have (reading off the containers):

Gear Oil: Sta-Lube "GL-5 PLUS" New-Generation Hypoid Limited-Slip Gear Oil (SAE 80W-90)
Additive: Sta-Lube "Equa-Torque" Limited Slip Differential Oil Additive

Are these what I need to be using? I'm assuming that I would need to use the whole bottle of additive. I'm just not sure about the weight of the gear oil--if what I've got is what I need to be using.

As far as actually changing the gasket and everything--as I've never done it before--I'm just assuming that it's a simple matter of removing the nine bolts, cleaning the gasket surfaces, and putting the new gasket on. Then I have to torque all of the bolts to somewhere between 22-25 ft/lbs of torque each. Lastly, I just put in the fluids through the cap on the back of the cover. Is this pretty much the correct procedure, or is there something else I should know? (Now that I think of it, I do need to know this: how do I know when I have enough additive/oil mixture? I know that the fluid capacity is 1.7 qts, but I'm not sure if I should measure that outside of the rearend or what.)

Thanks for the help...

 

sounds like you pretty much got it under control, unless a nine bolt requires something special, i've never even seen a nine bolt in person

 

i'd run mobil1 or amsoil synthetic oil and gm posi additive, nothing but gm additive reguardless of what the oil says. i believe the amsoil says it doesn't require any additives.

 

Stay away from "Sta-Lube" products (JUNK), Amsoil is good & the GM additive is fine.