The lubricants covered by this specification are intended for use in the precision bearings of inertial guidance gyros, accelerometers and other suitable instrument bearing applications. To allow the user the option of using a specified oil with the optimum viscosity and operation temperatures for the application, the lubricants in this specification are classified into five different grades of oils according to their viscosity properties. Prior to using these oils, their performance should be verified in each application. Recommended ambient temperature ranges for the five grades of oil are shown in table VI.