A system for measuring an oil retention volume of a first member of an engine lubricating system, the injected oil flowing inside the first member mixed with a first air volume, the mixture forming a first fluid, the measuring system including an oil injector at the inlet of the lubricating system; a first flowmeter to measure a first oil flow rate at the inlet of the lubricating system; a second flowmeter at the outlet of the first member to measure a second flow rate of the first fluid at the outlet of the first member; a measuring device to calculate a first value representing a quantity of oil in a volume of the first fluid flowing inside the first member; a calculator to calculate a third oil flow rate at the outlet from the second flow rate of the first fluid measured and the first value calculated and the instantaneous oil retention volume in the first member from the comparison of the first oil flow rate with the third oil flow rate.