Originally Posted by
Amesja
Sorry if I came on a bit strong in my wording.
I wouldn't personally add grease without removing the old stuff other than something that has grease-zerts on it for that purpose. Adding grease on top of old grease in a non-sealed open system like that of a bicycle hub/bearings seems just like forcing the contaminations on the outside of the grease further into the system.
Two places I do this, one is new assembly, where I don't think the factory uses adequate lubrication. (Saving half a cent on grease per hub adds up if you make a million of them, and you don't worry about warranty returns.) The other are things that it's not worth the effort of fully disassembling, like cup-and-cone bottom brackets. It's not worth taking the fixed cup out to inspect it, and you're not going to get all the grease out of the shell unless you use an unreasonable amount of solvents.
Zerk. With a K. Named after its inventor, Oscar Zerk. He also invented the hubcap.