CV joint grease compatibility.

[asand1]

I will be rebooting a CV joint very soon and was wondering how compatible black CV greases are with each other. My guess is that they are all of the same chemistry. This is a fairly new axle that just started leaking. I really don't want to go crazy cleaning the grease out of the joint as I know there is no contamination yet. I would rather just install the new boot and add some new grease.

 

[Olas]

Cv grease is moly in a lithium soap, pretty universal.

 

[Cardenio327]

We always "go crazy cleaning the grease out of the joint". Non-chlorinated brake cleaner will clean it up in a hurry. You have to take it apart completely anyway to change the boot, right? If it is clean enough to eat off of you will easily find any excessive wear or a cracked cage as well.

 

[AttackingMid]

There are many different formulations that may or may not be compatible with one another if mixed. Best to clean out the old and replace with new unless your certain of what is in there.

Someone said they are all lithium based with moly. That is not true. Lithium base with moly is a common aftermarket grease that is supplied with replacement boots for Rzeppa joints commonly used on outboard joints in automotive applications - probably because it's cheap.

It's hard to find information on what a given manufacturer uses as OEM grease, but many use a polyurea based grease with moly (if Rzeppa) or without moly (if tripod). Some modern polyurea greases claim to be compatible with the typical aftermarket lithium based CV greases, but historically the two have been considered incompatible.

There are other formulations. Redline's CV-2 is a calcium based grease, and SWEPCO's 101 is a clay based grease just for a couple of popular examples.

Bottom line is that it's definitely safest to clean out and replace the old grease entirely.

AM.