NRW Design Billet Oil Cap

For nearly two decades, BMW enthusiasts have dealt with the same frustrating issue—a factory oil cap design that has been prone to seeping and leaving oil residue across the valve cover. From the E46 and E9X platforms through the F8X generation, this has remained a common complaint.

The issue became even more apparent to us after we introduced the world’s first aftermarket aluminum S65 valve cover. Customers would occasionally report what appeared to be a leaking valve cover, only for us to determine that the oil was actually originating from the factory oil cap. To address the problem, we even began including brand-new genuine BMW oil caps with our valve covers, believing a fresh OEM cap would resolve the issue. Unfortunately, the leaks persisted.

As engineers, we weren’t satisfied with simply accepting the problem.

Our first solution was the NRW Design Ultimate Oil Cap—a multi-piece billet assembly featuring a threaded funnel attachment and an optional -10 ORB port for those requiring additional crankcase ventilation or custom plumbing. While highly functional, we recognized that many enthusiasts simply wanted a reliable, OEM-style replacement without the added complexity.

So we went back to the drawing board.

The result is our new single-piece billet aluminum oil cap, precision machined from 6061 aluminum and designed to deliver exactly what the factory cap never could: a leak-free seal, OEM+ appearance, and long-term durability. It retains a clean, period-correct look while permanently addressing one of BMW’s longest-standing annoyances.

Beginning immediately, every NRW Design valve cover will include this billet oil cap at no additional cost as part of our continued commitment to delivering the highest-quality products possible.

For our existing customers, we’ll also offer a limited opportunity to purchase the new billet oil cap at our cost as a thank-you for your continued support. It will also be available separately for BMW owners who simply want to upgrade their factory cap without purchasing one of our valve covers.

At NRW Design, we don’t just manufacture performance parts—we solve problems. We believe this is the most complete OEM-style oil cap currently available, combining premium materials, factory-inspired aesthetics, and a permanent solution to a problem that has existed for far too long.