For topping up - even in the warm season - use only a mixture of antifreeze concentrate with lime-free clean water.
Attention: To continue driving, you can also fill in clean water, especially in summer. However, at the earliest opportunity, the concentration of the composition should be adjusted with antifreeze.
Models 518i, 520i, 525i: When the engine is cold (coolant temperature approx. +20°С) The coolant level should be at the mark on the expansion tank or slightly higher.
Models 530i, 535i, 524td, 525td/tds: Cold (coolant temperature approx. +20°С) The coolant level should be at the mark on the expansion tank.
To avoid engine damage, fill a cold engine with cold coolant.
Caution: When the engine is hot, open the cover carefully. Danger of injury! When opening, put a rag. If possible, open the cap when the coolant temperature is below +90°C.
When opening the cap, first unscrew it a little to release the pressure. Then fully unscrew and remove the cover.
If the coolant level drops rapidly, visually inspect the leaks.