Cooling system for internal combustion engine

A cooling system for an internal combustion engine, comprising:

• a radiator configured to radiate heat from cooling water for the internal combustion engine;
• a radiator side cooling water route configured to circulate the cooling water through the radiator and the internal combustion engine;
• a bypass side cooling water route configured to circulate the cooling water through the internal combustion engine while detouring the radiator;
• a changer configured to allow the cooling water to flow through the radiator side cooling water route and the bypass side cooling water route if a temperature of the cooling water for the internal combustion engine is not less than a threshold value and configured to allow the cooling water to flow through the bypass side cooling water route while not allowing the cooling water to flow through the radiator side cooling water route if the temperature of the cooling water for the internal combustion engine is less than the threshold value;
• a heat radiation amount varier configured to vary a heat radiation amount from the cooling water in the radiator;
• and
• a controller programmed to control the heat radiation amount varier such that the temperature of the cooling water is less than a prescribed temperature that is a temperature higher than the threshold value if a load exerted on the internal combustion engine is not less than a predetermined load and configured to control the heat radiation amount varier such that the heat radiation amount from the cooling water in the radiator is increased if the load exerted on the internal combustion engine is less than the predetermined load as compared with if the load exerted on the internal combustion engine is not less than the predetermined load.