Opti-4 4 Litre SAE10W-40 4 Stroke Engine Oil: Opti-4 is the highest quality petroleum engine lubricant available, and is formulated specifically for the severe demands of power equipment.Opti-4 is a unique blend utilizing patented Eutectic additive technology for anti-wear characteristics combined with the industry's highest standard for anti-corrosion and thermal stability. Through the use of the Eutectic additive, Opti-4 extends the life of any 4-cycle power equipment engine by reducing friction, heat, and wear.