Quicksilver - Premium Plus 2-Stroke Marine Engine Oil Synthetic Blend 858025Q01. Overview. When you've been on the water long enough, you learn to recognize the gear you can count on - and the gear that just talks a big game. Quicksilver Premium Plus 2-Stroke Marine Engine Oil is the kind of product that's quietly dependable. You don't notice it when things go right, and that's exactly the point. It's designed for boaters who push their engines hard - full throttle through open water, or long ho