Mercury - 4-Stroke Engine Oil Filter Lubrication System Marine Coated Steel 866340K01. Overview. Every boater knows the feeling of turning the key and hearing that smooth, confident hum from a well-protected engine. It's the sound of clean oil moving through clean pathways - exactly what this Mercury Marine oil filter is built to support. Part number 866340K01 isn't flashy, and that's the point. It's a dependable piece of hardware designed to keep one of your engine's most important systems heal