- Hydrometer, commercially available, as well as at gas stations.
Checking the frost resistance of the coolant should be carried out before the onset of the cold season, especially if clean water was added.
Warm up the engine so that the upper hose connected to the radiator is warm.
Carefully open expansion tank or radiator cap, see section "Checking the coolant level".
Draw liquid into the hydrometer and use the float scale to determine the density of the liquid. In our latitudes, frost protection down to -30°C should be provided.
Adding BMW Concentrate
Example: As a result of measurement with a hydrometer, it was obtained that frost protection is provided up to -10°C. In this case, it is necessary to drain 3 liters of coolant and add 3 liters of pure concentrate. Table refers to 10.5 l cooling system capacity (320i,325i) On all other models, the values are reduced by about ⅓.
Attention: Only top up with nitrite-free antifreeze recommended by BMW.
Close the radiator cap and after a test drive, check the frost resistance of the fluid again.