Don't use the can of general purpose grease you find at your box or auto stores (the light creamy yellow stuff). When it degrades it gets "wet" and seeps out of the gear housing and gets all over the place...even when you're not using the tool. I've had luck with high temp bearing grease, but what is best to use is a thick paste grease (which I can never find local). I'd say the next best thing to do is find a tool service dealer (Milwaukee, DeWalt, etc.) and see if they will sell you a service pack of grease. OR You can go online and order some grease from a manufacturers tool parts website.