Any kind will do. I think I had some Permatex around so that's what I used. It won't take much. I probably used a glob about the size of a peanut on each screw. My thought process was that the silicone sort of acts like a nut, not letting the screw move / vibrate / twist. Plus, it should help seal up the hole a bit. And remember - soon as you feel the screw bottoming out - stop. Since you're going into a surface that's about the thickness of a single thread, it's easy to strip.