Ok, so i have the ez lube axels or whatever they are called now. I will use them after i finish my break job. I really dont see how a normal hand pumped grease gun will push out the back seal. Hell, i have a hard enough time trying to pry out the rear seal with a hammer to repack them. The new seal is always tight goung in also. I can see if you re use an old seal, or dont put the seal in correctly that you might blow out the rear seal. But under normal operation. I cant see it happening. Now with that said, i would repack by hand every 5 years or so to check the bearings and races and such. But i plan on using the ez lubes for a few years for annual greasing after its set up.