Mercury - Quicksilver Water Separating Fuel Filter Kit Fuel System Component Corrosion-Resistant Steel 18458Q4. Overview. Clean fuel means a healthy engine, and the Mercury Marine 18458Q4 Quicksilver Water Separating Fuel Filter Kit makes sure of it. Designed for 1996 and newer Mercury and Mariner V6 EFI outboards, this kit combines a 10-micron fuel filter with a blue water warning sensor to keep contaminants and moisture out of your fuel system. It's engineered to deliver dependable protection,