If you get a message in the cockpit of your vehicle that there is not enough coolant in the expansion tank, you should act as soon as possible and refill it. Either you fill up with distilled water for the time being, or you can immediately turn to a proper coolant additive.
What you have to pay attention to, that the following article briefly explains:
Refill distilled water and mix with previous coolant:
It is no problem to add distilled water into the coolant circuit. The distilled water does not react with the already existing residual coolant. However, temperatures outside should not fall below 5 ° C. Otherwise it may happen that the mixture with the distilled water freezes earlier than it would otherwise.
Here it is recommended to test this by means of a tester. Such a tester is available for a few dollar on Amazon:
This should be avoided if you do not know which liquid was previously filled! Please refer to your manual or ask your authorized dealer.
Why is it dangerous to mix different coolants? For example, many vehicles use the standard "G48". Mix this G48 now with the radiator protection "G12", then it creates a dangerous acid, which can then eaten aluminum parts and clog the cooling lines.
This can lead to serious problems with your engine. Therefore, be sure to refill with the correct coolant.
