Does anyone know of problems adding synthetic bearing grease to normal bearing grease ?

I know it can be done no problem with oil but is it the same thing with grease?

Most manufacturers caution against mixing greases with different bases eg lithium base, soap base, etc.

I've always used the recommended grade and type but never knew if what I was using had the same base as what the manufactuter originaly put in. I found the same is true with gear oils. How do you know?

 

To specifically answer the question, my '91 Legacy Subaru FSM states:

"Each oil manufacturer has it's base oil and additives. Thus, do not mix two or more brands( Except engine oil)."

 

They don't give any reason.

 

Based on this, for a bearing I would clean out all the old grease, or push all the old stuff out in the case of applications like propeller shafts, double cardan joints, etc.

I found the same is true with gear oils. How do you know?

I was thinking about motor oil.

Thanks for the reply.

I'm asking cause the axle replacement I was suppose to do last week has been postponed to next monday and all I have to do right know is to think and worry...

I'm not removing the bearings but only replacing the inside bearing oil seal. I want to add a little grease behind the seal to keep the lip lubricated. I was thinking about synth grease cause it is more water proof than others and the inner seal is where water usually finds its way inside and ruin the grease and bearing.

The two kinds of grease will only «touch» so maybe there will be no problem.

But I'm taking your opinion into consideration.

Thanks again.

You should be OK. There's no way around it. You are not really mixing them in the bearing. When I did a wheel bearing replacement, I used a little different grease to grease the seal too.

May be someone else has had this experience and can help.

I made a search «grease compatibility» on Google and found some interesting info.

Seems to be a complex question. The fact that incompatible greases can result in both liquifying at operating temp can make someone a little anxious about this.

Here's one page that gives a compatcompatibility chart

http://www.ieee-kc.org/library/craft/greasecompat.htm

Would someone know what exactly is the grease type - tickening base being all important - used by Subary in their cars wheel bearings

Bump...

and a Happy New Year to everyone!