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A rapid and precise oil consumption measurement in an automotive engine can be made in 5-7 minutes by a radiometric method. Several hours are usually required for conventional methods. The radiometric method consists of tagging the engine oil with a radioactive tracer, 1,2-dibromo-octadecane containing bromine-82. This material undergoes combustion with the oil, and the radioactive hydrogen bromide is extracted from the exhaust gas with one molar sodium hydroxide. Scintillation counting is employed to determine the amount of radioactivity recovered, which in turn is proportional to oil consumption. Oil consumption measurements were determined over a speed range of 1500-3000 rpm and over manifold vacuum ranges of 22-2 in. Hg. It was found that the presence of lead, either as engine deposits or in the gasoline, interfered with the recovery of hydrogen bromide. Therefore, this method is restricted to nonleaded engines.