The difficulties of maintaining efficient diesel engine performance at 0 F and below are discussed. Problems of cold starting, such as fuel requirements, starting aids, and application of heat are developed. Establishment of a winterizing procedure is needed for adequate diesel operation. Engine cooling systems could be equipped with shutters with thermo controls to prevent heat loss. Properly designed shrouds around the radiator will maintain warmth and improve fan and shutter efficiency. Also, air induction and fuel systems and batteries have to be adapted to maintain efficient zero weather operation.