Fleetguard® ES Compleat OAT is a Life-of-the-Engine 1,000,000-mile coolant. This nitrite, amine, phosphate, and silicate free Organic Additive Technology/Extended Life Coolant technology is compatible with silicone seals and is our most versatile coolant for use with Light-Duty and Heavy-Duty Diesel applications as well as Natural Gas, Gasoline, and Battery Electric applications. Due to low maintenance requirements and compatibility with many system contaminates, ES Compleat OAT is the preferred technology of most OEMs.