Notorious Rocket Scientist
Join Date: Mar 2008
Location: Baltimore, Maryland
Polybutyl Cuprysil (sometimes also called Polybutyl Cuprosil) is simply silicon grease with a copper pressure additive. It is used extensively in brake systems to lubricate caliper bolts and the like because the silicon grease base can withstand higher temperatures than Lithium soaps or organic soaps and the copper additive can take higher pressure than Molybdenum additives.
This very same composition is often sold as high-temperature anti-seize compound, so if you can't find it being sold as a brake caliper lubricant you might find it as an anti-seize. I'll also bet you can order it from Summit Racing.
Lee E. Brown
"Greetings from Herkheimer Industries!"