Look at things this way. An IGH hub is most similar functionally to a gearbox or differential on your automobile, though obviously lighter duty. If you look, you won't find a single maker of these products that recommends using teflon. There must be a reason, and though you may not know why, you'd be wise to stay on the well trod path of oiling your hub with oil.

Note also that IGH hubs (like most gear box systems) depend on splash lubrication to circulate the oil as the wheel turns and keep all parts lubed long term. Lubes that dry up do not splash, or circulate will rapidly wear off the mating surfaces leaving then unprotected.