Wheel Bearings

TravelinDog wrote:

klutchdust wrote:
"Used to be, likely still applies, not a good idea to mix different types/brands of grease. "

I would really like to see some proof or research/testing done by a reliable source to back up that statement. Having serviced hundreds of semi trailer units and not knowing what grease was used previously, it was a rarity, rarity that a bearing in our fleet of over 10k units ever had a bearing failure. A bearing was only serviced when the unit was brought into the shop for a brake change. That could be anywhere from 1 year or 5 years. Servicing wheel bearings every year is just nonsense. I call malarky on that one.

I agree 100%.
The bearings don't car what kind of grease is in there. The important thing is that there is grease and the bearing never run dry.
Mixing different greases has never been a problem in over 40+ years of cars, trucks and trailers.

The bearings may not care, but one needs to consider that not all greases or grease brands use the same thickener and the thickener may not be compatible between the two greases.

My Dad always mentioned about being careful of what type of thickener was in the grease and not to mix greases which did not have the same thickener.

HERE is a good read on mixing greases and compatibility.

" The test results are shown in Figure 1. Every grease was incompatible with at least one other grease. The most incompatible were aluminum complex, calcium complex, clay and polyurea-thickened greases.

The most common effect was substantial softening, however lithium grease sometimes hardened. Interestingly, barium grease blends looked like grease on the bottom and oil on the top, which may indicate that the second grease thickener was liquefying upon mixing. It is important to note that even if thickeners are generally compatible, two greases may contain clashing base oil or additive formulations.

Also, not all thickeners of the same group are compatible with each other. Polyurea grease is an example of this as two polyurea grease formulations in specific cases may not be compatible with each other."

In a nutshell, mixing greases with incompatible thickeners can soften or liquify the grease, can breakdown the grease or harden the grease.

HERE is more info from same website above that may be of interest.

" Unlike the compatibility of oils, which is most often related to interactions of the additives in the products (and sometimes the nature of the base fluids themselves), the compatibility of greases is most often related to the thickener types of the products to be mixed (although base fluid compatibility is also important).

How to Determine Grease Compatibility and Why It's Important also provides an indepth look at grease compatibility.

Grease compatibility is often confusing to grease users, even though most grease manufacturers produce compatibility charts. This is because the charts from the various manufacturers often disagree with one another on certain thickener-type combinations. In bygone days, when simple soaps and clay were the primary thickener types, compatibility was relatively straightforward.

Lithium and calcium soaps were compatible with one another, and neither was particularly good when mixed with a clay-based grease. Today, with not only the aforementioned thickeners – but also complex soaps, polyurea, calcium sulfonate and even more exotic thickeners used in many greases – the issue of compatibility has become much more complicated. A typical grease compatibility chart is shown in Figure 1."

I would encourage you to review the material in the links as there is a lot of good to know stuff there.

Basically, I try to buy the same brand and type of grease, if for any reason I am not able to buy that grease I have been using I simply clean the bearings and surfaces any old grease that is present and repack with fresh grease from the new brand.

While you most likely will not encounter a problem mixing grease brands and types, it may not be ideal to do so. For the small amount of grease used for each wheel it is a small price to pay for knowing it was done right.