Yes, TCP (Tom Cat Piss) is used a lot in aircraft designed to run 85 octane AvGas, where 100LL causes problems. It helps prevent the dreaded "morning sickness" too - where valves hang when cold from lead deposits. Lead Phosphate is a lot softer and easier to get rid of then Lead Oxide, and is also less conductive on the plug insulators.
100 Low Lead has a LOT more lead than the old 85 octane leaded avgas.