Synergy 10W To 40 is a fully synthetic high mileage engine oil designed to help slow or eliminate the symptoms of worn engines such as knocking, loud tappets, oil leaks, and consumption. It is manufactured with high viscosity base oils and a top tier anti wear package to offer outstanding wear protection for critical engine parts. This contains special viscosity stabilizers and detergents to help stop oil leaks, clean hydraulic lifters and prevent the buildup of harmful sludge. Synergy 10W To 40 contains top notch friction modifiers to further reduce wear, and protect pistons as well as turbochargers.