A method for operating an internal combustion engine wherein the internal combustion engine to be operated is supplied with lubricating oil via an oil circuit. A measurement value of a total base number and/or a measurement value of the viscosity of the lubricating oil currently used in the oil circuit for the lubrication is detected. Dependent on the established measurement value of the total base number and/or dependent on the established measurement value of the viscosity an exchange oil quantity for the oil circuit is determined. Currently used lubricating oil to an extent corresponding to the exchange oil quantity is removed from the oil circuit. New lubricating oil to an extent corresponding to the exchange oil quantity is supplied to the oil circuit.