An internal combustion engine has an oil pan divided into two chambers that communicate with each other. The first chamber is at a distance above the bottom of the oil pan, which is also the bottom of the second chamber. Because the bottom of the oil pan is cooled by the slip stream the oil in the two chambers are at different temperatures. Suction lines lead from each chamber to a thermostat valve that connects them to a discharge line. The thermostat valve operates such that when the engine is cold the oil supplied to the discharge line is relatively hot oil from the first chamber and when the engine is hot the relatively cool oil from the second chamber is supplied via the valve.