This classification establishes a series of definite viscosity levels so that lubricant suppliers, lubricant users, and equipment designers will have a uniform and common basis for designating, specifying, or selecting the viscosity of industrial fluid lubricants.

This classification is used to eliminate unjustified intermediate viscosities, thereby reducing the total number of viscosity grades used in the lubrication of industrial equipment.

This system provides a suitable number of viscosity grades, a uniform reference temperature, a uniform viscosity tolerance, and a nomenclature system for identifying the viscosity characteristics of each grade.

This system implies no evaluation of lubricant quality and applies to no property of a fluid other than its viscosity at the reference temperature. It does not apply to those lubricants used primarily with automotive equipment and identified with an SAE number.

This classification is applicable to all petroleum-base fluid lubricants and to those nonpetroleum materials which may be readily blended to produce fluid lubricants of a desired viscosity, that is, lubricants for bearings, gears, compressor cylinders, hydraulic fluids, etc. This classification is used to eliminate unjustified intermediate viscosities, thereby reducing the total number of viscosity grades used in the lubrication of industrial equipment. The lubricants shall be classified according to viscosity grades: ISO VG 2; ISO VG 3; ISO VG 5; ISO VG 7; ISO VG 10; ISO VG 15; ISO VG 22; ISO VG 32; ISO VG 46; ISO VG 68; ISO VG 100; ISO VG 150; ISO VG 220; ISO VG 320; ISO VG 460; ISO VG 680; ISO VG 1000; ISO VG 1500; ISO VG 2200; and ISO VG 3200.

1.1 This classification is applicable to all petroleum-base fluid lubricants and to those nonpetroleum materials which may be readily blended to produce fluid lubricants of a desired viscosity, that is, lubricants for bearings, gears, compressor cylinders, hydraulic fluids, etc.

1.2 This classification is applicable to fluids ranging in kinematic viscosity from 2 to 3200 cSt (mm²/s) as measured at a reference temperature of 40°C. In the category of petroleum-base fluids, this covers the range from kerosine to heavy cylinder oils.

1.3 Fluids of either lesser or greater viscosity than the range described in 1.2 are, at present, seldom used as industrial lubricants. Should industrial practices change, then this system, based on a mathematical series of numbers, may be extended to retain its orderly progression.