I guess I'm one of the few that oils all my stuff regularly. Been doing it for years. I've seen no issues from it. If you have a traditional straight line sander oil in one of those is fairly essential for it to work halfway decently. There is a fill hole on those. Little angle die grinders need grease or they die real quick. If you decide to use oil just a drop and do that fairly regularly. If you wipe down your work before primer, etc. it shouldn't be an issue. Stick with straight petroleum based stuff. Nothing with silicone or exotic additives in it.