Mercury - Quicksilver 5W-30 4-Stroke Full Synthetic Marine Engine Oil Premium Marine Lubrication Full Synthetic Protection 8M0148474. Overview. Anyone who spends time on the water knows how much trust we put into our engines. Long runs across open bays, slow crawls through winding channels, quick throttle bursts to beat the tide - your motor sees it all. And the oil inside it quietly carries the weight of every one of those moments. That's why the Mercury Marine part number 8M0148474, Quicksilve