Mercury – 25W-40 Synthetic Blend Oil | Four-Stroke Engine Protection | 8M0078623Mercury 25W 40 Synthetic Blend Oil Four Stroke Engine Protection 8M0078623 Overview This 25W 40 synthetic blend is the kind of oil most boaters keep on the shelf because it helps a four stroke run smoother and last longer. It handles those long days when the engine stays warm for hours, and it doesnt break down as quickly as lighter blends. Fresh oil like this usually quiets the motor a bit and gives it an easier, more relaxed feel. Its a steady