Coolant, also known as antifreeze, is essential to the proper operation of a vehicle's engine. However, most motorists don't bother to change it regularly. If this is the case for you, this inattention could cost you financially, as it is your car's engine that will be damaged in the long run. Coolant flows from the engine to the radiator and is used to keep the engine's temperature stable at around 100°C. Cooling prevents engine overheating, which can lead to premature engine wear, reduced performance, broken cylinder head gasket or deformation of engine parts. You must therefore regularly drain the cooling system to expel any air that has infiltrated the system.

When to replace the coolant?

It is necessary to check the cooling level regularly, on average every five weeks. To do this, simply look at the expansion tank containing the liquid.  Check the coolant to avoid potential damage. The level should be between the "max" and "min" markings on the jar or nurse cup. Top up, if necessary, with coolant sold at car centers or stations. Above all, never use water, except in an emergency. Be careful, you must use a coolant that is compatible with your own. According to vehicle manufacturers, coolant deteriorates and becomes brown or opaque (deposit-laden) after two to five years of use. Its condition should be checked approximately every 10,000 km. In addition, the efficiency of the coolant can be affected by changes in temperature. Changing the coolant is a rather complicated operation and should be done with care, so you must be careful of air bubbles in the system. Like all oils, it is strictly forbidden to discharge it into the environment, as it is corrosive.

How to change the coolant?

Changing the coolant is not only a way to put new coolant, but also to remove the air that has entered the cooling circuit. To change the coolant, you must bleed the cooling system. Of course, you can call an auto centre or a garage. You can also carry out the operation yourself, but only if you take all the necessary precautions. This liquid is irritating, so it is important to protect yourself. The coolant must be changed when the engine is cold. To do this, you must take a container with a capacity of 10 litres and place it under the radiator drain cover. Then open the drain cover and allow the old coolant to drain out. Close the radiator drain plug again when nothing more is draining out. Then rinse the system to remove any traces of used fluid. After this, let the engine warm up for ten minutes to allow the water to circulate. Let the engine cool down, and when it is really cold, drain the water in the same way as the old fluid. It is necessary to rinse the engine several times until the water is clear. In a container, mix two litres of coolant with two litres of water. Pour this mixture into the radiator, then restart the engine until bubbles start to escape, and then screw the cap on. Before adding the coolant to the jar, the engine must be cold. The coolant level must be between the "min" and "max" indicator lights.

Replacing the coolant: how often?

The service life of the coolant is limited. Over time, it will become dirty and oxidize. In general, a worn-out coolant turns a brown colour, which is visible when checking the levels. In this case, the liquid loses its efficiency: it is less resistant to freezing, it cools the engine less, and its acidity can damage the seals. The coolant should be changed every two to five years. How long a coolant can be stored depends on its technical properties. For example, organic liquids can be stored for a longer period of time than mineral liquids. To be sure when to replace the coolant, you should consult the manufacturer's recommendations in your vehicle service manual. A coolant that is not replaced on time may cause the engine to overheat.