Grease Compatibility And Why The Charts Aren’t Exactly Accurate

I never really thought much about grease compatibility years ago when I first started working on my vehicles. I was uninformed figuring “Grease is Grease.” (Kind of like the “Oil is Oil” people.)

I had a standard grease gun (back then cars still had grease fittings) and would pick up a tube of grease when I needed it at Sears, Bradley’s, K-Mart, Benny’s or wherever I happened to be when I remembered I needed it. As long as the price was cheap and it fit my gun, that’s all I cared about.

In 1992 when I became an AMSOIL Dealer, one of the things I put in stock was a case of the multi-purpose grease. Didn’t think anything of it at the time other than if someone wanted grease, I’d have some.

Got to the point when I needed more grease for the gun and was going to go pick some up when I remembered I already had some. Put a new tube of AMSOIL grease in the gun and finished greasing the linkage and suspension .

In 1992 I was still driving older vehicles that didn’t have the best grease seals on the steering linkage and ball joints. As soon as I started pushing grease in I would get a little water then some water/grease mix would come out of the boot/seal. Didn’t think anything of it. This was normal for all my vehicles for the prior 25 years.

The next time I greased fittings I didn’t get any water, only a little dark grease mixture. I’m guessing this was a mix of the original grease I had been using and the AMSOIL grease. Still didn’t think much about it until the next time when all I got was a little red AMSOIL grease. Since then I have never gotten any water out of a fitting lubricated with AMSOIL.

To get back on track, when I finally came across a Grease Compatibility Chart it finally dawned on me that maybe I should be checking compatibility. Reviewed the charts and, whenever anyone ordered grease for the first time, reminded them to check the compatibility with what they were previously using. (Just because 2 greases are rated NLGI#2 GC-LB doesn’t mean they are compatible.)

A while back I added a link to the AMSOIL Grease Compatibility Chart. For most people, it’s probably a good start. At least it should help prevent any major problems. But today I read an article and learned that the Compatibility Charts really aren’t perfect since they are only looking at the filler/thickener and not the base oil or additives used in the grease.

If you are greasing machines or equipment that must remain in service (because being Out of Service creates major problems), check out this article (How To Determine Grease Compatibility And Why It’s Important) from the Lube Tips Newsletter published by NORIA. It may just save you some down time.

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