I've always used high-temp moly grease for brake guide pins, after trying things like anti-seize. I just did my rear brake pads, and the guide pins seemed to have rubber dampers and a clear lube. Everything was in excellent shape, so I put it back together without adding lube. This looked like dielectric grease (silicone grease), which I use for a lot of things with rubber seals. It's good to 400*F, I'm thinking this is the stuff. Googling around, silicone grease seems to be the proper lube for brakes, I'm planning to use it for my front brakes. Anyone heard any different?