The grease seal really shouldn't if everything is clean, but it's just a rubber flap resting against the spindle. I've noticed mine get a little roughed up using 4wd. It's a cheap part if it is FUBAR and it's probably not a bad idea to repack the hubs if you go through a lot of mud or water in 4wd. It's a 30,000 mile maintenance item, but I've been doing mine ever 5-10,000 depending on how much slop I go through.