I've been using a Metabo SDS drill for a while but am unsure whether to grease the sds bit or not - When I bought the drill I greased every time, but after a few months hard work the end cap of the sds chuck popped off. It seems the grease had made the rubber seal very soft & sticky, and this had then stuck to the chisel as it moved back & forth, even though I had kept everything as clean as possible. I obtained a new chuck from Metabo and have been worried to grease the drill bits for fear of the same thing happening!! The drill bits slide nicely as long as everything is clean, though the application of some sort of lubricant does seem appropriate.... anyone know if there is a special sds grease or something?.. what about silicone lube?