Jan 2005 I installed disk brakes on my 5th wheel which came with never lube bearings. In March 2009 all four bearings turned up bad. Mileage traveled was around 40 to 45,000. The problem was failures in the plastic seals. These bearings have been used by the two major brakes suppliers that I know of. All four of my bearings were replaced under warranty. I am told that the vendor who supplied the bearing corrected the problem around two and half years ago. So if you see any grease leaking on the inside of the tire rims or around the hub or if you can hear unusual noises coming out of the wheels, and your bearing are over two and half years of age, you might want to have your bearings checked out.