A coulometric SO2 monitor has been developed to measure SO2 generated from combustion of S in oil to determine engine oil consumption. Sulfur-free fuel (<2 ppm S) is used to eliminate background levels of SO2. Addition of an SO2 standard gas to the engine during tests insures accurate normalization of sampling system flows and quantitative measurement of engine oil economy. Precision of the SO2 microcoulometer technique was better than ±8%. The SO2 microcoulometer is used during steady state engine operation, and may be used in determining oil consumption from individual cylinders. Existence of engine oil consumption via an aerosol mechanism is investigated and measured. Effects of engine operating temperature and positive crankcase ventilation (PCV) on engine oil economy are given.