Abstract: The invention concerns a device and method for cooling and preheating, especially of transmission fluid, of an internal combustion engine, with an equalization tank, with at least one radiator, which can be connected by means of an engine thermostat when a predetermined temperature is reached in the cooling loop, and with a water/oil heat exchanger. It is prescribed according to the invention that the forward stream (1) of a single water/oil heat exchanger (5) be branched off in the heating phase by means of a valve unit (3) essentially from the main cooling loop (12) of the internal combustion engine (17) and that its forward stream (1) in the cooling phase be taken by means of the same valve unit (3) essentially in the coolant side stream (13) from the low-temperature region (14) of the radiator (4) or a separate low-temperature cooler (14a) connected in the side stream after radiator (4, 4a).

Abstract: In order to control the temperature of the transmission oil of a motor vehicle driven by a liquid-cooled engine, a coolant/transmission oil heat exchanger is provided. The coolant stream supplied to the heat exchanger is miscible in a thermostatic valve from recooled and non-recooled coolant in order to achieve a desired temperature. Preferably the thermostatic valve is controlled by the temperature of the transmission oil, but it is also possible to have two expanding material elements as control pistons of the thermostatic valve, with one control piston being provided in the oil chamber of the thermostatic valve and the other control piston being provided in the coolant mixing chamber of the thermostatic valve. It is also possible, for purposes of precontrol, to electrically heat at least one of the control pistons.