Differential fluid

What type of fluid would you suggest using for an 85 IROC?

What do you mean, what weight or what brand manufacturer?

Limited slip?

Power steering fluid

if it's a new differential use some synthetic... if not I'd use regular...

Use gear oil, AKA manual transmission fluid... I'd tell ya what weight I use but I don't remember lol

gear oil is 80/90 gear lube

There are different weights... but mines somewhere aroudn there.

If it's posi/limited slip don't forget the additive

Power steering fluid
WTF? LOL :screwy:

Anyways, how do I tell the difference between LS and a standard gear? I'm pretty sure whatever is on the car is still stock.

Mobile 1 synthetic 80w gear oil is what I would use. Make sure to get a good gasket. It may seep a little since its synthetic but it good stuff to use. The only difference in oil between posi and not posi it whether or not to add the additive. And pretty much all that the additive is is a little bottle of synthetic oil. There may be differences between formulas but essentially thats what it is. Some people who use full synthetic gear oil to begin with do without the additive but I would just because I paranoid. :)

The limited slip formula replenishes some of the clutch pack friction material that was lost when draining the case.

For wieither or not you have an open diff or not there is an rpo code sticker under the console armrest. Somewhere on there if you see, I think it's G80 or G85, soemthing like that it's a lsd (which I believe most Irocs were). Do a search ont he forum, Erik (89IROC&RS) mentioned the exact code number a few times. My memeory is not what it used to be.

www.thirdgen.org (http://www.thirdgen.org)

they have the list there

or jackit up so the rear wheels are off the ground, put it in neutral, and spin one wheel... if the other wheel spins youve for an lsd, if it doesnt you either have an open diff or a broken LSD

That's a lot of useful infrmation! Thanks guys!

Yeah, I was just kidding when I said power steering fluid...

Is this a Borg Warner 9-bolt? Many WS6 cars between 1985 and 1988 came with them. It's a stout axle. It still uses cone clutches for the slip control, and requires GM1052358 friction modifier additive - Even with synthetics.

As for the lubricant itself, even if it is old, Mobil 1 75W90 (M2198-YP) is the only way to go. You'll improve efficiency and reduce drivelime losses on even an old, loose rear end. I'd suggest you consider the same lubricant package for even a 7.65 Saginaw 10-bolt, except drop the additive if it's an open diff.

Yeah, I was just kidding when I said power steering fluid...

I knew that :rofl: it was funny though.

Blue Bowtie: I am actually not sure what is on the car because it is in storage yet and I did not own it long enough last year to even mess with anything. From what Morley was saying though, it sounds like it *should* have a Saginaw 10 Bolt LSD.

well, as I said, lsd was pretty much there all together on irocs, Z28 it was optional.