You can use pretty much what ever spins your crank. Occasionally you might stumble upon an Oring that doesn't like your chosen lube. You usually won't find that out until the Oring rebels. Mostly I use a light lithium grease. That chain lube in your pic I suspect would be to light. Another...
In this application I think one side of the slug need not be faced. The one faced side will have the emitter board glued to it. While the unfaced side will have an electrically isolated positive battery contact glued to it ala arc LS.
gadget lover had some valid points to consider. About the alloy of brass. I don't care about color. Heat transfer would be main concern. I'll need to solder to it as well. This is going to be the heat sink for a mod of an Arc LS. So it must screw into the head. If the mod works out the way I...