Just curious, as I only dunk my trailer 6-8 times per year. I inspect my bearings and grease periodically, and everything looks fine. I keep my boat on the water and only trailer a couple of times per year. Do I need to change the grease and repack bearings after a certain amount of time regardless of condition or only when it appears to have water in it or worn out. I've had the boat about four years now (18 footer with a single axle trailer) and so far haven't changed or repacked cause it still looks good. Am I asking for trouble? Thanks in advance for any responses.