Pour Perm-O-Seal into your radiator while engine (and water pump) is running. Perm-O-Seal speeds through the water channels, seeks out holes and swells shut as soon as it comes into contact with air. Perm-O-Seal stays suspended in coolant fluid and draining or flushing will not affect a seal. Perm-O-Seal’s unique rust inhibitors and water pump lubricants help your coolant system work at peak efficiency.