"Battery grease is what your talking about. Its used for corrosion on DC powerplant connections, and is conductive."
That's something else. Dielectric grease is used for corrosion but is not conductive. Like you say, though, you can get grease that is conductive.
"There should be no arcing on any tube socket if it is in good condition and no grease is needed.
Some sockets can be damaged by arcing caused by a failure of the tube, if this happens the grease will not protect anything."
Good answer. Unless your stereo system says Ford or Chevy on it, best to leave your system ungreased.
"Don't use it on audio gear. (Unless you get the stuff made specifically for high end audio applications.)"
That's just me being a smart ass. Pay no attention to it. There really is no audiophile grade dielectric grease (That I know of). Sorry if I confused anyone.