Mercury - High Performance Oil Filter MerCruiser Sterndrive & Inboard Series Synthetic Filtration Media 858004K. Overview. There's a certain comfort in knowing your engine is protected long before you push the throttle forward. Clean oil isn't just maintenance-it's the lifeblood that keeps long summer cruises, early-morning runs, and family weekends running smooth. That's why so many boaters stay loyal to Mercury's High Performance Oil Filter 858004K. It's built for those of us who want the conf