Each of these Stihl attachments have a threaded cover into which lubricant should be added to keep the tool's internals lubricated and running smoothly. I do not have the manual for any of these attachments, so I do not know what Stihl recommends. Does anyone know what Stihl recommends, or have a suggestion? I was thinking of using a thick gear lube, like Amsoil's SAE 250 racing gear lube. How well would this work? Any other suggestions?