Evans Prep Fluid is specifically formulated to hygroscopically absorb any water-based coolant remaining in the cooling system after initial drain. Because certain parts of the cooling system might not drain out with gravity, and it would take too long to disconnect every pipe etc., installing a scavenging fluid is the most practical method of removing all the water-based coolant.
The Prep Fluid is not formulated to chemically clean the engine of rust and scale, but the process of circulation and draining will help remove any loose sediment.
Evans Prep Fluid must be used before converting from a water based coolant to Evans Waterless Engine Coolant.
