WARNING  
The brake fluid constantly absorbs moisture from the air; this lowers its boiling point.
If the boiling point of the brake fluid is too low, vapor pockets may form in the brake system when the brakes are applied hard (e.g. when driving downhill). This would impair braking efficiency.
You should have the brake fluid renewed at regular intervals. The brake fluid change intervals can be found in the Service Booklet.

Only use brake fluid approved by Mercedes- Benz. Information about approved brake fluids can be obtained from any authorized Mercedes-Benz Center.