Mercury – 10W-40 4-Stroke Marine Engine Oil, 1 Gallon | FourStroke Lubrication Series | Mineral Base Oil | 8M0148477Mercury 10W 40 4 Stroke Marine Engine Oil, 1 Gallon FourStroke Lubrication Series Mineral Base Oil 8M0148477 Overview Oil changes arent the glamorous part of boating, but theyre the part that keeps the whole story going. When youre miles from the ramp and the water turns unpredictable, you want to know your engine is protected on the inside, not just rinsed clean on the outside. Good marine oil gives you that quiet confidencelike the motor is running