Bar's Leaks Carbon Fiber Block Seal Head Gasket & Cooling Sealant is the strongest antifreeze compatible repair on the market. A key benefit of this product is the material stays in the cooling system to seal up any future minor cooling system leaks the vehicle might have. It can be used with all types of antifreeze including green or blue (silicate-based) and extended life red/orange or yellow (OAT/HOAT) coolant. No draining of the cooling system is required. For racing applications it works great in straight water.