Mercury - Grease Gun Maintenance Tool 3 oz Cartridge Compatible 74057A6. Overview. A smooth-running boat needs proper lubrication, and the Mercury Marine 74057A6 Grease Gun makes that job quick and easy. Designed for use with 3-ounce Mercury grease cartridges - including 2-4-C and Extreme Grease - this compact, pistol-grip gun is built for one-handed operation. Its sturdy construction and rigid feed tube give you precise control in tight spaces, whether you're servicing your engine, trailer bear