"IP 226-2004 Calculation of viscosity index in kinematic viscosity of petroleum products" specifies the method of calculating viscosity index (VI) of petroleum products by kinematic viscosity at 40 ° C and 100 ° C. The viscosity index is an indicator of the viscosity of petroleum products with temperature. The higher the VI, the smaller the viscosity change with temperature. The standard applies to petroleum products such as lubricating oils and fuel oils, and provides detailed calculation formulas and steps to ensure the accurate calculation of viscosity index. The results can be used for quality control, Product Research & Development and performance evaluation, and are widely used in petroleum and related industries.