Since the beginning of time every trailer we've ever owned have all had oil bath hubs. And as usual when a wheel seal goes out you pull it apart, clean everything up, check the bearings/spindle install a new seal and re-assemble. How do you know when the sealed grease bearings die? I mean I know the obvious "when the wheels fall off" but I just wasn't sure if there was anything to look for. Do they start to leak and sling grease in the brakes like the oil hubs? We bought a used trailer recently and it has grease hubs and wasn't sure on maintenance or what to look for.