The NRW-Design BMW Billet Oil Cap was engineered to address one of the most common and persistent issues affecting BMW engines across multiple generations. From naturally aspirated M engines to modern turbocharged platforms, the factory plastic oil filler cap can allow oil seepage that leaves residue across the valve cover, even when replaced with a new OEM cap.

The issue became especially apparent during the development of NRW Design's aluminum S65 valve cover. In several cases, what initially appeared to be a valve cover leak was traced back to the factory oil cap. Replacing the original cap with a brand-new Genuine BMW component did not always resolve the problem, confirming that the factory cap design itself could remain a source of seepage.

NRW Design initially developed its Ultimate Oil Cap as a multi-piece billet assembly with a threaded funnel attachment and an optional -10 ORB port for custom crankcase ventilation applications. While that design remains well suited for specialized builds, many BMW owners needed a simpler solution that retained the factory-style operation and appearance.

The NRW-Design BMW Billet Oil Cap was developed as a direct OEM-style replacement. Each cap is precision CNC-machined from a single piece of 6061-T6 billet aluminum and uses factory-style locking tabs with a dedicated gasket sealing surface. This construction provides improved rigidity, consistent engagement, and long-term durability compared to the original plastic cap.

Available in hard anodized black or a raw machined finish, the cap features laser-etched NRW Design branding and is compatible with both OEM and NRW Design Viton oil cap gaskets. The understated design maintains a clean, period-correct appearance across older BMW M applications while also complementing modern engine bays.

Designed and manufactured in the USA, the NRW-Design BMW Billet Oil Cap is included with current NRW Design valve covers and is also available separately for BMW owners looking to replace the factory oil filler cap with a durable billet aluminum alternative.

Product Details

• CNC-machined from 6061-T6 billet aluminum
• Single-piece billet construction
• Direct replacement for the factory BMW plastic oil filler cap
• Uses factory-style locking tabs for OEM-style operation
• Precision-machined gasket sealing surface
• Compatible with OEM and NRW Design Viton oil cap gaskets
• Available in hard anodized black or raw machined finish
• Laser-etched NRW Design branding
• Designed and manufactured in the USA

Additional Compatibility

• Also fits many additional BMW applications using the same factory oil filler cap design.
• Compatible engine families include S65, S85, N54, N55, B58, S63 and other BMW engines with the corresponding factory-style cap interface.
• Verify compatibility with the vehicle and engine before ordering.