Mercury - Premium Plus 2-Stroke Marine Engine Oil Synthetic Blend 858026K01. Overview. There's something reassuring about knowing your motor's protected, no matter how long you're out there. That's the feeling you get with Mercury's Premium Plus 2-Stroke Marine Engine Oil, confidence built into every drop. Whether you're carving through a choppy inlet or easing into calm morning water, this oil keeps your outboard running smooth and strong. It's not just about keeping the parts lubricated, it's