[Dave W]

I do it the old fashioned way and have since --- well as long as I've owned a towed trailer.

There are a couple reasons, well actually more. The first is that it takes at least a full tube of four buck/tube grease to lube those bearing and fill the hub initially. Then if you really want to do it right, you still need to pump at least a half tube of grease back in there every time you get the urge. That discolored grease that you see oozing around the spindle nut washer (yes, the washer, not the Zerk) is only from that outer bearing. You can only guess where that cruddy stuff from the inner bearing goes. Yep, it mixes with the new and helps keep that hub filled plus adds a bit of unsprung weight.

Then there is that seal. It really is not a very good part and the land that it rides on plus the land behind it are pretty small for what they need to do to prevent fouling the brake shoes and magnet surfaces. Take a look at the attached photo. This is a brand new spindle on a 6K axle. Larger are virtually identical and you will see the seal surfaces - the last one before the forging flaw ith the grease hole just in front of that surface. Not noch height to restain a seal - lesss ten .0625 (1/16").

Repacking wheel bearings (and inspecting brakes) is NOT a nice clean project. It does take some time and can be expensive if you are not a DIYer - but still better then sitting along an interstate in West Overshoe on a Saturday evening with a smoking hub.

Your choice on how you want to lube bearings. But as always, the above is only my opinion though based on my many yeras and many miles hauling an RV. I have even gone to the (minor) cost of plugging the wheel's hub caps hole with a part from etrailer.