A study was undertaken to compare the oil consumption characteristics of large and small automobile engines. A fleet of 120 employee-owned vehicles was operated in typical passenger car service in the Cleveland, Ohio area between April and December, 1974. Two test oils of equal viscosity but widely varying volatility characteristics were used for the study.The results showed no correlation between engine size and oil consumption. The results also showed no difference in oil consumption between the test oils. The results did show the expected trend toward higher oil consumption with increasing engine mileage. The development of a standardized laboratory procedure which correlates with oil consumption in passenger cars is recommended.