What component is used with water to create coolant for an engine's cooling system?

The component used with water to create coolant for an engine's cooling system is ethylene glycol or propylene glycol. These compounds are antifreeze agents that lower the freezing point and raise the boiling point of the mixture, helping to maintain optimal engine temperatures under various environmental conditions. By mixing these glycols with water, it creates a fluid that effectively transfers heat away from the engine, prevents engine overheating, and protects the engine from freezing in cold weather. This combination of water and glycols also helps to reduce corrosion within the cooling system, further extending the life of the engine components.