While waiting for paint to dry I did a bit of a google on the subject, amazing the ideas some people have, the ball and hitch being self lubrication on one site tickled me but since the hitch contact to the ball is a small cup shaped bolt head sort of thing I doubt the cast hitch will lubricate, it's really what ever takes your fancy and as for dirt roads and dust chewing up your hitch, I haven't really noticed it on tow ball or trailer 5th wheels, plenty of dust hanging off the overspill of grease around the edges but not on the mating surfaces, if you don't give it a wipe every so often then you could have scouring......................plastic would be good so long as it didn't eventually work its way into the latch mechanism and jam it, never heard it doing it though .....................