Prestone® Radiator Stop Leak’s patented formula quickly stops leaks in radiators, water pumps and heater cores while also protecting against pitting and corrosion.
NOTE: Do not use in a dirty or partially clogged radiator. Use Prestone® Flush + Cleaner first.
- With engine off and cool, shake well and add entire contents to radiator and fill with Prestone® 50/50 Antifreeze/Coolant. For systems larger than 12 quarts, use two bottles.
- Run engine at the highest heater setting for 10 minutes after reaching normal operating temperature.
- Turn off, allow to cool. Fill with Prestone 50/50 Antifreeze/Coolant. Check fluid frequently, top off as necessary.
Prestone® Radiator Stop Leak takes sealing performance to a higher level. Its unique combination of natural and synthetic components provides the ability to seal leaks up to 0.016" X 0.5". What makes this possible is the size, strength, and durability afforded by fibrous particles, the same materials in bulletproof vests.
Prestone® Radiator Stop Leak particles have been chosen to seal even large leaks without interfering with the flow through the radiator and heater core tubes. It also boosts corrosion inhibitors to protect against pitting and corrosion, which cause radiator leaks.