Mercury - Oil Pressure Gauge L-H Engine Protection Monitoring Black Face Brushed Bezel 79-8M6020048. OverviewThis L-H oil-pressure gauge gives you a simple, steady read on how the engine's lubrication system is holding up while you're running. The needle moves in a calm, predictable sweep, so changes stand out without you hovering over the panel. Out on the water, it reacts the way you'd expect-idling, cruising, or pushing into some chop. It's the kind of gauge that quietly helps you stay ahead