Mercury - Xtreme Grease, 8 oz. Lubrication 92-8M0071838. Overview. Every mechanic and boater eventually settles on a grease they trust, and this stuff is one of those "always keep a tube on hand" products. Mercury's Xtreme Marine Grease is made for the ugly jobs-parts that get hammered by heat, load, water, and salt. It hangs on where cheaper grease washes out, and it keeps moving parts from chewing themselves up after a long season of hard use. If you're the kind of person who does your own ste