Evans Prep Fluid is a waterless cooling system flush designed to remove water-based antifreeze after draining the cooling system of an engine. Prep Fluid should be used when block drains are unavailable or cannot be removed. It is not a substitute for thoroughly draining the cooling system and related components. Please refer to installation instructions to determine the amount of prep fluid needed. Prep Fluid is NOT intended to be a stand-alone operating coolant, but as a flush only.