My 2012 189FDS has grease zerks on the hubs.
Generally speaking the axle suppliers say that "grease" works best for situations where the trailer is likely to be sitting for a period of time between uses, and "oil bath" works best for when the trailer is used constantly (daily).
Having said that, we have a flatdeck gooseneck that only gets used once every few weeks, and the oil bath hubs have been totally reliable for us.
But then, all of the hubs I've have had over the years that use grease have been totally reliable too. Regular maintenance has helped, I'm sure ! I'm pretty good about maintaining things.