How long does coolant last in a car?

Coolant, usually composed of water and antifreeze, can own several properties that improve performance with the support of additives. For example, a corrosion inhibitor can be added to the coolant to protect your engine’s metallic surfaces against corrosion. Over time, these features will degrade as the fluid gets more and more acidic. This deteriorated liquid can trigger severe harm to your engine by failing to control the temperature. Therefore, manufacturers suggest replacing the coolant periodically.

It is recommended you change coolant after the first 210,000 km (140,000 miles) or 120 months, then every 30,000 km (20,000 miles) or 24 months. 

Keep in mind there is a possibility the coolant might leak from a worn reservoir. Such leakage can lead to cooling system failure and severe damage to your engine. To avoid this, it is advised to regularly check whether the reservoir shows the proper coolant level or any signs of cracks.