Was the tung oil pure (the only one that I know of is Old Masters) or a "tung oil finish"? Pure tung oil is extremely expensive. Tung oil finish is usually a blend of polyurethane, linseed oil, mineral spirits, and a little tung oil. If it is pure tung oil, I don't like a film finish on top so I would either use carnauba wax or nothing. I would never entertain the idea of using a dust magnet soft wax. If you used a tung oil finish, then it really is not necessary to add any more polyurethane, but a carnauba wax job might give it a nice shine if that is what you would like.