you could put diff fluid instead of using the grease. i only know of locking the center diff for more all wheel power or putting diff fluid in the center and all the diff so it doesnt slip as much. locking the front will give you posi traction in the front for more pulling and less steering, not a very good combo. go to the cen web site and see what they recomend for silicone fluid in the diff,their recomendations are very good.