Use Amsoil, they make a great gear lube.

 

A coupla tips from someone who's done this job a few times now:

1- Leave room for the friction modifier when you put in the gear oil. If you pour gear oil up to the overflow, you'll have a hell of a time pouring in some f.m.

2- Go easy on the modifier. You can add it in steps. Once you pour in the new gear oil, get it worked into the clutches. Go do figure eights somewhere. If you start chattering, especially turning left from a stop, add 4 oz and do some more figure eights. If you still get chattering, add 4 oz more and repeat!

I've used Red Line and Royal Purple in mine and needed 8 oz both times. Some people don't need it at all, that's the point of determining where you are and going from there.

 

I just changed mine i use redline.

 

I used Mobil 1 and started with 2 oz of friction modifier. The limited-slip chattered, so I had to add another 2oz and it reduced the chatter to a reasonable amount while allowing my LS to actually work very well.

When I got my Goodyear Silent Armors, I added another 4oz because I wanted to save the tires

Limited-slip still works OK, but not as well as with only 4 oz total.

Anyway, long-story-short, when I used plain-jane Mobil 1 synthetic 75w140, it NEEDED friction-modifier for my limited-slip

 

Dont have time this week to do it and no one had Mobil 1 around town so i just went to Ford to get a qt of the 75w140 and some friction mod. to top it off. I am going to fix the pinion weep and change the fluid all in one shot when i get a chance in a couple weeks!

 

How are you going about fixing the pinion weep? Mine's been weeping ever since I changed gears, never has dripped so I'm not worried about it. I cleaned the pinion sealing surface up really well and used a new seal, but it weeps... Are you planning on using a speedy sleeve or something else?

 

If the seal is weeping, CHECK THE BREATHER.

 

Hey Art,
I didn't have to add any FM with M1. Is that an indication that my LS is wearing out?

 

First thing I did, but good advice for UGA33

 

Could be... Not sure if there's a Mobil 1 out there WITH friction modifier, or if for some reason the stuff I used was different. I'll see if I can find the bottle of leftovers.

 

I was under the impression that Mobil 1 has friction modifier. My unit performs good, no chatter, but I'll admit I haven't really tested the slip since the fluid change.

 

I saw some mobile 1 bottles that said "LS" on the side and said it was for limited slip differentials, so maybe it has some in there. I'd rather be able to control the amount to confirm that it is correct.

 

I will do that right now!

 

Mobile 1 makes two types. 1 is LS and 1 isn't. LS has the mods in it.