I have had them on my boat trailer for 8 years. I give them a shot or three twice a year. No problems so far.
They seem to hold enough grease that it's not an issue.

 

i have them on my trailer and wouldn't go without. i know my seals are leaking and i don't put the wheels in water of any depth so a couple pumps of grease before we pull the trailer and its good to go. this doesn't mean i don't check the bearings at least once a year! most seals will leak grease out with the beaing buddies! grease under pressure when warm will have to go somewhere! my .02...

 

http://www.bearingbuddy.com/faqs.htm#7

 

i've used bearing buddy on past trailers and never had a problem. Only added grease when the spring was extended, also i never had the rear seal blow out ... but i'd change the seals and clean the bearings every other year. My new trailer has a built in grease system ... i add a 1/4 squirt in each wheel after every tow, then i'm sure the grease in there is hot and soft so the new grease can flow into the bearings. I also have used mobil 1 red grease for years ... seams like it's a little better flowing in the winter.

 

I went out and bought a mini grease gun with a six pack of grease tubes. Gonna give all my trailers a squirt everytime I take them out. Better to be safe than sorry. Trailer dealer said just pump until you see the grease start to move and then it should be fine.

 

if your trailer doesnt get put in water, then you could easily go 1,000 miles or more. consider this, most small cars(like my little aspire i drive to work) has almost as small bearings on the rear wheels as the traier and i'll bet they havent been greased more then 3 or 4 times in 100,000 times. the smalled bearings / more weight on them heat up(not alot) more w/ the load is about the only reason you would ever go thru grease, which wouldnt be a heck of alot. so i would say maybe every couple of trips you could add a sqirt. just a thought.

 

If you run in the rain, does that have the same type of effect on the trailer as dipping it in the drink? Sounds like a goofy question, but it has been raining in Chicagoland all summer long.

 

no, running in the rain is not the same. when bearings and hubs get warm and you put the tariler in water( like a boat trailer) its like a vaccum and if your seals are bad, will suck water into the bearing hub assy.

 

well said. as long as the seals are good theres no problems running in the rain.