A method includes: (a) determining an engine speed of an internal combustion engine, wherein the internal combustion engine has an engine wall, and the engine wall has a wall temperature; (b) determining an engine load of the internal combustion engine; (c) determining a wall-reference temperature as a function of the engine load and the engine speed of the internal combustion engine; and (d) adjusting, using a cooling system, a volumetric flow rate of a coolant flowing through the internal combustion engine to maintain the wall temperature at the wall-reference temperature.