This standard specifies the test method for determining the friction coefficient of lubricating oil using a four-ball wear testing machine. This standard applies to the determination of friction coefficient of lubricating oil. The values in this standard use the International System of Units (SI) units, but some equipment that meets this standard uses cm-kgf, so the cm-kgf unit is retained. This standard covers certain hazardous materials, operations and equipment, but is not intended to make recommendations on all safety issues related thereto. Therefore, users should establish appropriate safety and protective measures and determine an applicable management system before using this standard.