Adding fluid to the cooling system (Audi 100 C3)

It is not recommended to add pure distilled water to the cooling system to restore the normal level, as this changes the ratio of antifreeze fractions, anti-corrosion additives and water. The standard amount of water in the cooling mixture is 40%, which allows the engine not to defrost at temperatures down to -25°C.

If you still had to add clean water to the system, check the density of the cooling mixture before the onset of winter cold and restore the normal ratio of components.