What does this mean with regards of what the owner needs to do? I have 6000 miles on my 2015 Winnebago travel trailer that has self-lubing wheel hubs. I have never had them lubricated.
If greased bearing rather than oil bath, be VERY careful shooting grease in there with a grease gun via a Zerk fitting. It's very easy to blow grease out the back grease seal and get grease on your brake drums and pads. Greased brakes don't work very well. Many experienced RVers advocate pulling the hubs on this type of setup, cleaning and inspecting the bearings, and packing them by hand annually or every 12,000 miles - whichever comes first.