A cooling system is disclosed for an internal combustion engine. The cooling system may include a first cooling circuit having a first coolant that flows through cooling channels of an engine, and a second cooling circuit having a second coolant that flows through a charge air cooling component. The cooling system may further include a drain line adapted for fluid communication with the first and second cooling circuits. A first temperature responsive valve disposed on the second cooling circuit may be included, the first temperature responsive valve configured to open to allow mixing of the first and second coolants when the temperature of the second coolant is at a preselected minimum temperature. Also included may be a second temperature responsive valve disposed on the drain line and configured to open to drain both cooling circuits when the temperature of the first and second coolants is at a preselected minimum temperature.