Sunoco Sunvis 646+ Ashless Hydraulic Oil is a ultra premium lubricant used mainly in John Deere, Hitachi and other off-road equipment Hydraulic Systems. Sunvis is a line of Sunoco Lubricants that covers a variety of hydraulic applications. The "600" series is a group of premium hydraulic fluids that do not contain zinc anti-wear additives and is referred to as Ashless. the "+" designation means this lubricants has a High Viscosity Index which provides excellent flow properties in extreme temperature conditions as well as highly efficient machine operation. 46 represents the thickness of the oil which is an International Standards Organization Viscosity Grade (ISO VG) 46.