Our Fleetguard and Cummins water filters remove rust and debris from your cooling system. Your cooling system keeps engine temperatures at the right level to dissipate heat and maintain the right operating conditions. The right coolant conditions promote optimal fuel economy. Fleetguard Cummins and Donaldson coolant filters remove contaminants, minimize the risk of filter plugging and keep your engine running efficiently. Balance is the key in Coolant water Filtration. Estimates project that more than 40% of heavy-duty engine repair costs are related to the cooling system.