Abstract: A mixing valve for an engine cooling system includes a cylindrical chamber, a main thermostatic element mounted in the chamber, first and second inlets axially spaced along the chamber, and a sleeve connected to the thermostatic element and movable in response to the changing temperature of liquid flowing through the chamber from a position completely blocking flow through one inlet and leaving the other inlet totally open to positions gradually permitting flow through the first inlet and restricting flow through the second inlet. A second thermostatic element is positioned outside the body of the mixing valve and has a piston axially aligned with a piston of the main thermostatic element and engaged therewith to adjust the starting position and range of movement of the sleeve. The second thermostatic element is responsive to parameters such as external air temperature, engine load, engine speed, etc. The double thermostatic element arrangement is also disclosed in connection with poppet valves.