Fiberlock is a permanent sealant solution with a liquid glass base. Is designed as a long-term solution for a coolant leak. Lesser products are semi-permanent and only designed as short term fixes. They can also cost more down the road. If your vehicle has a traditional cooling system with the radiator cap, you can add the sealant directly to the radiator. Otherwise add the sealant directly to the radiator hose. Like we show here. Use a funnel to help avoid unnecessary waste and prevent spills. A half bottle of fiber lock treats up to 10 quarts of engine coolant. The Fiberlock travels through the cooling system until it reaches a crack. The fibers then fill the crack and form a web like weave for strength. As air in the cooling system passes over the patch, the sodium silicate within the Fiberlock hardens to create a permanent seal. Since the cooling system is pressurized the seal will typically get pushed deeper into place. As this happens, additional Fiberlock is pressed in to strengthen the seal and provide additional durability. Replace the upper radiator hose; make sure the hose is attached securely. If you added the Fiberlock directly to the radiator, be sure to replace the radiator cap.