If the engine is still warm, you should only carry out a visual inspection of the coolant from the outside, if possible: The mostly white or transparent liquid container can often be recognized by the “Caution, danger of scalding” symbol. A min and a max mark are drawn on it. When the engine is cold, the fluid level should be in between.
- If it’s too high: Off to the workshop.
- If it is too low: Check the cooling system for leaks. If you top up fluid and the level is low again after a short time, or you discover moisture spots under the car, you should visit a workshop as soon as possible.
During the visual check, you should also pay attention to the condition of the liquid: If the cooling water is discolored or if there are particles floating in it, this indicates corrosion. A film of oil indicates that the cylinder head gasket is defective.
How to add coolant
With the engine cold, open the cap of the fluid reservoir and top up with fluid until the level is between the Min and Max marks .
What coolant do I need?
Since the cooling system is a complex cycle that is vital for the engine, the motto is: The right mixture makes the difference!
There are concentrates on the market that which you can mix yourself, and also ready-mixes in which the water content is already sufficient. Every vehicle manufacturer specifies the correct ratio in the operating instructions. This is the only way to ensure optimal frost and corrosion protection, says vehicle expert Christian Heinz from TÜV Thüringen.
The different colors of the coolant are used for quick orientation and to ensure that coolants with different specifications are not accidentally mixed. However, the decisive factor when choosing the right product is not the colour, but the type identifiers such as G11, G13+ or G000. To do this, read your car’s manual or take a look at the expansion tank: the identifier is stamped or printed on the plastic.
If you are unsure which coolant is used, it is better to visit a specialist workshop.
May I top up with tap water?
If you need to top up with coolant and don’t have the right agent at hand : Stay away from any other coolant than the recommended one, but use distilled or deionized water, says vehicle expert Christian Heinz from TÜV Thüringen.
Tap water is taboo: There is a risk of limescale deposits in the circuit. Only in extreme emergencies, for example if you have broken down due to an overheated engine, can you use still water to bridge the gap.
Water refilled: What about the antifreeze?
All common coolants contain sufficient antifreeze. However, if you had to top up with a little more water, if you are not sure whether you have mixed the coolant correctly or if the coolant is older: Test spindles for under ten euros, which display the existing antifreeze on a scale. Basically, the medium to -50 degrees should not have any problems.
Changing the coolant: When is this due?
The Shelf life of coolants is not unlimited. Pay attention to the recommendations of your vehicle manufacturer. For some passenger cars it is recommended to use all 50.000 kilometers to change the coolant, for others it is up to 50.000 kilometers – some do not recommend a change at all.
25 Wiping water additive in the cooling circuit: what to do?
A common mistake: confusing the coolant with the wiper water additive, which is also colored. If you have put this agent in the cooling circuit, you should have the coolant changed as soon as possible in a specialist workshop. The components of the wiper water additive could otherwise attack the cooling circuit and lead to corrosion.