Abstract: A cooling system for cooling an aircraft turbojet engine includes a first heat-exchanger for exchanging heat between a heat-transfer fluid and a lubricant of the turbojet engine, a second heat-exchanger for exchanging heat between the heat-transfer fluid and air, and a circulation duct for circulating heat-transfer fluid in a closed circuit. The cooling system further includes at least one regulating device for regulating the heat drawn from the lubricant, controlled by a control module of the regulating device that is configured to receive information according to the various flight phases.