Billet vs. OEM: Why Upgrade Crank Seal Guard for BMW Performance Engines Maintaining a BMW performance engine necessitates paying attention to every little detail. The crank seal guard is one crucial component that many people ignore. The selection between original equipment manufacturer crank seal guards and billet crank seal guards determines whether your engine is reliable or will face significant damage for daily driving or when you are competing on track. Click here for more info: https://paradigmengineering.co/blogs/news/billet-vs-oem-why-upgrade-crank-seal-guard-for-bmw-performance-engines