Wax formed in cold diesel fuels can settle, causing fuel storage and distribution problems and unexpected vehicle failures. The extent of these wax settling problems depends upon fuel, storage conditions, and the design of vehicle fuel systems. New Wax Anti-settling Flow improvers, WAFI, reduce crystal sizes and keep wax dispersed in the fuel. Improved performance of cold fuels treated with WAFI has been demonstrated in storage tests, a diesel fuel rig, and in diesel trucks on a cold climate chassis dynamometer. Most improvements are found in diesel vehicles with fuel systems that are sensitive to wax related failures. Benefits from the application of WAFI are: reliable cold fuel performance for consumers, improved refinery economics and the ability to increase diesel fuel production to meet growing demand.