I'm waiting for my new #3500 axles from Inland RV and intend to try Oil Lubed hubs. I've picked up two sets of XL ProLube kits to install when things come together...
Kodiak Trailer Components - XL Prolube Kit
These kits are a quality product...the oil seals are the oil bath type that rotate inside themselves, and not against the axle stub. With this type of seal you won't have any wear on the stub, as the seal doesn't 'rotate' there. The key to oil bathed hubs are the unique design of the seals, used in millions of miles on big rigs.
This type of seal has been used on large trucks and trailers for years and years, and allow the bearings to be constantly be bathed in oil to run cooler...no grease is used what so ever!
The only disadvantage I could see on an RV trailer would be if one were to 'rub off' (when backing into camp, etc.) the outer hub oil retainer caps...you'd lose your lube, where as with grease packed hubs, if you lost the outer cap, the bearings would still have SOME lube, if you caught it in time!
I like the convenience of taking a quick look at the oil level and knowing the bearings are well lubed! No repacking will ever be required...except for leak.
Any experience out there? Any comments?
They retail for about $50 per pair (1 kit with lube)...I actually got mine from West Marine.