Mercury - Oil Level Gauge White Face 2-1/8" (52 mm) 79-8M0052873. Overview. The Mercury Oil Level Gauge (79-8M0052873) makes it easy to monitor your engine's oil level right from the dash. It's a clean, classic design with a white face, bold black markings, and a glass lens for clear viewing in all light conditions. Built to fit a standard 2-1/8" (52 mm) dash opening, this OEM gauge connects to compatible SmartCraft systems when oil level sensors are installed, giving you a quick and accurate wa