Rockinger Silicone Oil is the perfect lubricant for guitar nuts.
Application: carefully wipe the small brush at the edge of the bottle and give only a very small amount of oil into the nut slots (maybe every second time you change your strings). Use a cloth to immediately wipe away excess oil. Silicon oil can hardly be removed of most surfaces, that's why you should be very careful with it. Silicon oil is non-toxic and physiologically safe. Keep out of reach of children. Bottle contains 20ml.