Alright its time to change the rear end fluid........ I was going through my service manual and it says roughly 2 quarts of fluid (3.75 pints).........now I also have been told that its 2.5 quarts......does anyone wanna clarify? i'm gonna change it out tomorrow

 

Go with whatever the manual says.

 

Just fill it till its runnin back out(parked on level ground)which worked out to be about 2.5 quarts on my 01 Gt.

 

Looks like I need another quart ....damn why cant they sell these things in half

 

ive always used 2 quarts with zero problems.

 

well i'll do a compromise i'll put 2 in which should be fine if not i'll drive over to the store and get more.

 

Youll need two quarts PLUS friction modifier unless it already has it.

 

Royal purple is da shiznit

I also have some friction modifier but theres not point in point it in since royal purple has it already

 

and amsoil is better, but thats another thread.
lol

 

nuh uh......

 

Buy 3 quarts, put in two, watch for it to start leaking out about halfway through the third. If you buy Mobil 1 Synthetic Gear oil or Lucas Synthetic or Amsoil, you will not need a friction modifier. If you do anything else, add the bottle of friction modifier FIRST! You want to make sure you get it all in there. Also, don't use ANY OTHER friction modifier except for Ford Motorcraft XL-3.

 

anything is better than RP

 

Care to clarify the warnings with some reasons? What's wrong with Equa-Torque, or Redline FM, or any of the zillion others (Some Dodge SUV's with class 3 and class 4 hitches from the factory use a special modifier but that's the only one I've ever known that was different) that are available?

FWIW, I use Redline heavy or light shockproof depending on what I'm doing and no friction modifier.

Friction modifier is only applicable to those people using clutch type posi-traction. Torsen, locker and spool users don't need anything but just plain GL-5.

 

Only reasons being whenever I did a gear oil change and didn't use the manufacturers recommend additive, I always ended up with noise.

1984 Z28, used something other than GM additive and had noise, added the GM stuff and noise went away.
1993 Dodge Dakota, same as above. Actually, used car dealer changed the gear oil 3 times before they thought to use the OEM stuff.
Working in the parts dept at a local Ford dealership had over a dozen people come in to buy the Motorcraft additive after experiencing the same problems that I explained above. I have Lucas Synthetic Gear oil in my 04 GT and the bottle CLAIMS that no additive is needed, but guess what...I have a slight noise when going around turns. So, out it will come and I will replace it with the XL-3 and Motorcraft Gear Oil.

I might just be an exception to the rule, but for my own piece of mind, I will install what the manufacture recommends. Now, if I install a different locker, I will go with whatever THEY recommend. Just my .
You all can use what you want.

 

Good explanation.
The dodge is covered in my experience. The greenish gross smelling junk that dodge uses in some of their diffs is different and I've never had anything work just like it in sensitive dodge diffs.

The fords, I've never had an issue with Ford at all. But I'll keep that in mind since I have a confirmable report of it happening more than once.

GM, I've seen more fluid incompatibilities with GM than any other maker except for Alfa Romeo. Never had issue 1 with their LSD's making noise after equa-torque but still, I'll probably take the advice.

See, even us guys that have done thousands (literally) diff lube changes can learn. I'm hoping to be slapping in a detroit locker inside a 9" soon so that'll take care of any need for me but it's good to have the info.