NO GREASE, for the reasons mentioned. I wipe the lens mount (body and lens) clean. To me, ANY grinding sound when mounting or dismounting the lens is NOT good. The lens should slide on and off smoothly and easily. It could be poor finishing, leaving a less than smooth mating surface. This is one place where cheap 3rd party lenses are saving $, vs. nicely finished mounts of Nikon, Canon, etc.