Mixing grease?

[SteveD2]

Today I took off a wheel on my boat's trailer for the first time since I bought it a year ago. I was pleased to find a "Bearing Buddy" and alot of grease. The grease is green (like the color of oxidised copper) and I have no idea what kind it is. I just bought a new grease gun and it came with "multi purpose lithium grease". Would it be ok to just pump some of that in on top of the old grease? I don't want to take it apart and re-grease the whole thing...I'm going to be selling it in a few months.

 

[Kestas]

Unless you know what the original grease is in the bearing, the two greases should not be mixed. Mixing greases with incompatible bases can result in an overly thin grease. Once the grease is changed out, then you can simply pump through new (same) grease each time. The dscision is yours.

 

[RB Shannon]

I would tend to clean out the old grease also, even if a chart states that two different grease thickeners are compatable the different additive packages and differing manufacturing techniques may cause an unwanted change in the mixed greases performance regardless. That's not something I would want to have to worry about pulling a boat down the highway 50 miles from home.
A greenish grease, might be Lubrimatic Marine a calcium sulfonate, or Massey Ferguson high temp, a polyurea...you just can't tell.

 

[Neil Womack]

On the BITOG home page is a link to a grease primer. Has a good chart of grease compatibility.

Though with bearings I would clean and then apply new grease.

 

[Drstressor]

You can generally mix any lithium complex based wheel bearing grease without a problem. However, you should use a marine grease, rather than a general purpose GL-2 lube in boat trailer bearings because the marine stuff has better corrosion inhibitors and generally a higher drop out point. Also, it is good practice to clean, inspect, and repack wheel bearing on a boat trailer each year. Finally, make sure that you use a "double cupped" boat trailer inner wheel bearing seal or the fancy ones sold by Bearing Buddy. If you use a standard automotive type grease seal with bearing buddies, the seal will leak grease (and let water in) if you fill the buddies up properly (with slight pressure).