After starting, the water pump circulates the coolant in the small cooling circuit. This takes place in the engine block, the cylinder head and the heat exchanger. In front of the heat exchanger is also the fan, which provides warm air in the interior. From an operating temperature of about 75-85°C, a thermostat ensures the opening of the so-called large cooling circuit. This now also includes the radiator and the expansion tank. In addition, the radiator fan provides cool air when needed, even when stationary or at particularly high temperatures. The heat from the engine is transferred to the cooling water and transported through the cooling system to the radiator. There, the heat is dissipated to the outside air, keeping the engine at operating temperature without overheating. This temperature is of great importance for engine performance, fuel consumption and thus also for pollutant emissions.
The coolant also always contains an antifreeze. In addition, alcohol and various additives are added to the coolant. This means that the radiator antifreeze is contained in the cooling system all year round. Pure water should only be topped up in an emergency, for example in the event of a breakdown. Water has its boiling point at 100°C and expands when it freezes; it also promotes corrosion in the cooling system. It is therefore unsuitable as either a coolant or antifreeze.
The tasks of the coolant are the removal of heat, frost protection and the prevention of deposits. In addition, of course, the coolant should not attack seals or hoses. Furthermore, coolant reduces wear caused by cavitation. This is the formation and explosion of small vapor bubbles.
The coolant is divided into the following types:
In general, the different types should not be mixed with each other, unless it is explicitly allowed to do so.
When buying coolant, many think that you just have to choose the same color of antifreeze, then it will fit. But the color of the coolant in the cooling system says nothing about the chemical composition! Each manufacturer may use its own color system. When buying coolant, therefore, pay attention to the specifications and approvals in the operating instructions or the labeling of the expansion tank. Mixing the same or different colors of antifreeze without observing the specification is not recommended.
VW and the chemical company BASF have developed standards for the antifreeze for their products. A few other manufacturers also follow these radiator antifreeze standards.
We have compared these standards in the following table:
|VW||VW Approvals||BASF||additional names||Color||Description / Notes|
|G11||TL-774 C||G48||C11||Green / Blue green||
|G12||TL-774 D||Red / Pink||
|G12+||TL-774 F||G30||C12+||Red purple||
|G12++||TL-774 G||G40||C12++||Red purple||
With the coolant, you should pay attention to the total amount, as well as the proportion of antifreeze. To check the total amount of coolant, look under the hood at the expansion tank. There are two marks on the coolant reservoir, the fluid level should be between "MIN" and "MAX". If it is below that, the coolant, including antifreeze, needs to be topped up. You can buy coolant either as a concentrate or as a ready mix. Do not fill up the antifreeze concentrate undiluted under any circumstances. Otherwise, the freezing point will be reached too early and the boiling point temperature and heat dissipation will be reduced. The concentrate should be mixed with distilled water, as it does not contain lime, minerals or other foreign substances. The mixing ratio of radiator antifreeze to water usually varies between 60/40 and 40/60. The exact mixing ratio is written on the products. Caution when refilling the radiator antifreeze: always let the engine cool down first before opening the cap, as it is under high pressure at runtime. After refilling, close the cap hand-tight and let the engine run for a moment. If the level of the coolant does not drop below "MIN", sufficient coolant has been added.
In addition to the total quantity, the proportion of radiator antifreeze must also be checked. To do this, the coolant in the vehicle can be tested for temperature resistance using a anti-freeze tester from Gefo, for example. Approximately every two years, the complete coolant including antifreeze should be replaced, as above all the rust protection effect is diminishing. For this purpose, a drain plug must be removed from most vehicles and the cooling system flushed through with water. It is essential to dispose of the old fluid properly at a recycling center.
With us you will find radiator antifreeze from the following well-known manufacturers:
The antifreeze for the car is available from us either as a concentrate or as a ready-mix. The overview listed on the product pages in the lower section, indicates for which vehicles the corresponding coolant is suitable. To do this, it is best to select the vehicle on the page, then the appropriate coolants are displayed. If you still have questions about the radiator antifreeze, contact our customer service with the vehicle data.
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