Continuous Measurement of Engine Oil Consumption Rate by the Use of 35S Tracer

In the measurement of engine oil consumption the conventional radiometric method is more rapid and precise than the drain-weigh method, but the former method-a batch type-is inapplicable to measurements in transient engine operations which are inevitable in real driving. In the present study, a reliable method was developed to measure continuously the consumption rate through all phases of engine operation. Oleic acid sulfide containing S³⁵ was selected as a radioactive tracer to be added to the engine oil. Engine exhaust gas containing the discharged oil was burned in an electric furnace and a gas burner and reacted with aqueous H₂O₂ solution, converting the S³⁵O₂ into H₂S³⁵O₄. A plastic bead scintillator used for the detection of β-rays from the aqueous solution was sensitive enough to measure the consumption rate as low as 0.4 g/h. Some informative observations were also made on the oil consumption of the engine in transient and steady-state operations by use of this new measurement system.