- Densimeter (to determine the concentration of antifreeze), which is available at a low price in stores selling motorsport accessories and is also often offered for use at petrol stations.
For safety reasons, it is necessary to regularly check the concentration of antifreeze in the cooling system coolant before the onset of winter, especially if the system has been refilled with clean water in between.
Warm up the engine until the top of the radiator feels warm to the touch.
Open the expansion tank cap carefully.
Caution: Do not open the cap when the engine is hot, see chapter "Checking the coolant level".
Suck in the coolant with a densimeter and determine its density by the position of the float (the densimeter scale is graduated in°C, and the measured value indicates the temperature above which the coolant will not freeze). In our latitudes, the concentration of antifreeze should prevent the coolant from freezing at least to a temperature of -35°C, which corresponds to a 1:1 ratio of antifreeze and water.
Adding BMW antifreeze
Please note: Since the radiator and heat exchanger are made of aluminium, only suitable antifreeze approved by BMW should be used.
Example: Measuring the concentration of antifreeze in the cooling system of a 530d car showed that the coolant is guaranteed against freezing to a temperature of -10°C. In this case, 3.4 liters of coolant must be drained from the cooling system and 3.4 liters of pure antifreeze must be poured into the system. This ensures that the coolant is protected against freezing to a temperature of -35°C.
Note: The table shows volume values for a coolant temperature of approximately +20°C.
Close the expansion tank cap and, after a test drive, check the concentration of antifreeze in the coolant again.
(You can read the original on the website «BMWMAN.ru»)