Castrol EDGE is our strongest engine oil. Advanced full synthetic, it has the strength to maintain a protective layer of oil between engine parts at all times. Why might you need full synthetic engine oil? Simply because today’s small but powerful engines operate at more than double the internal pressure of the engines made 20 or 30 years ago. This means that the pressure between two moving parts can be as much as 10 tons per square centimeter. Castrol EDGE 0W-40 A3/B4 with Fluid TITANIUM is formulated for prestige and high performance engines in both petrol and diesel passenger*, light commercial vehicles, naturally aspirated or turbocharged. The exceptional characteristics of Castrol EDGE 0W-40 A3/B4 ensure that all engine components, from the valve train to the bearings are fully lubricated to provide optimum engine performance and protection for today's modern engines requiring lower viscocity higher performance oils.