Genuine OEM BMW Oil Separator Crankcase Ventilation, part number 11151406789. This component is designed to separate oil mist and vapors from the crankcase gases before they are recirculated, ensuring proper engine ventilation and reducing oil consumption. It plays a vital role in maintaining engine health and meeting emissions standards. The separator is typically integrated into the crankcase ventilation system. Genuine OEM parts ensure the correct separation efficiency and longevity required for effective crankcase management.