Engine Coolant Performance in Late Model Passenger Cars 760631

A national survey of factory-fill coolants in 1972 to 1974 vehicles has shown that moderate or heavy rusty sediment was present in 23% of these coolants the first year and 36% the third year. Corrosion inhibitor depletion and dilution have additionally contributed to result in a minimum of 35 to 53% of cars requiring cooling system service, increasing over these three years. This survey, showing good agreement with extensive data reported before SAE in 1966, indicates that the cooling system still should be serviced, including flushing and refilling with fresh antifreeze-coolant at minimum 50% concentration, each year for best assurance of continuous, satisfactory cooling system performance in modern engines.