I don't put anything on the 3 PH balls. Any type of lube will just gather dust and make it like sandpaper. It is best not to use anything. We put thousands of hours on our farm tractors, never greased the balls and never had one wear out or become loose. For our CUTs, no one is likely to put 10,000 hours on them with the 3 PH so the balls will never wear out. If they become frozen due to lack of use, then some WD40 or other penetrant that evaporates in time works well to free them up.