A new antifreeze coolant has been developed for the heavy-duty diesel engine. This anti-freeze coolant has better anticorrosion performance than Supplemental Coolant Additives (SCAs) and has longer life than commercial permanent-type coolants. The new antifreeze coolant is composed of ethylene glycol and corrosion inhibitors.In glass ware tests, the new antifreeze coolant showed the best anticorrosion performance in cast iron, aluminum and other metals. The anticavitation pitting property and anti-oxidation property were also tested.In order to evaluate the new antifreeze coolant, a bench engine test procedure has been established. Since the new antifreeze coolant caused light cylinder liner pitting on bench test, antifoaminq property of the coolant was improved. The improved coolant showed excellent performance against cavitation-pitting and aluminum corrosion on engine bench and in the field.