Internal combustion system

An internal combustion system, comprising:

• an engine;
• a cooling circulation mechanism that circulates a coolant to the engine while cooling the coolant, the coolant adapted to cool the engine and containing ethylene glycol;
• and
• a temperature sensor that measures a temperature of the coolant having passed through the engine,
• wherein:
• the internal combustion system further includes a control device, the control device having:
• a number of starts counting unit that determines a cold start of the engine and counts the number of cold starts during a period until the coolant is exchanged;
• an accumulated amount of time measuring unit that measures an accumulated amount of time when the temperature of the coolant measured by the temperature sensor is equal to or higher than a defined temperature during the period until the coolant is exchanged;
• and
• an exchange determination unit that determines that the coolant needs to be exchanged, when the accumulated amount of time is equal to or greater than a defined amount of time and the number of cold starts is equal to or greater than a defined number of times.