Why are there so many methods for calculating dynamic viscosity in PRO/II?

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Isn’t it enough to simply divide viscosity by density? Why are there so many methods, and why do the calculation results differ from viscosity divided by density? O(∩_∩)O Thank you @homingpigeon. Kinematic Viscosity of the Liquid Phase: Liquid viscosities are determined from kinematic viscosity and density. For this calculation, the density (sometimes expressed as specific gravity) is calculated using the API method. To use this option, a KVIS method must be specified in the METHOD statement. A KVIS option is available only with the VISCOSITY(L) keyword. KVIS methods include rules for combining data from individual components in order to obtain a value for the entire liquid. Each KVIS method can convert between property values and index values; user-defined methods can implement either type of conversion or both. For the specific equations used by these methods, see the section on Special Methods for Liquid Viscosity in the PRO/II Component and Thermophysical Properties Reference Manual. The rules used by these methods can be found in the section on Special Stream Properties in chapter 8 of the Thermodynamic Data Keyword Manual. Simsci: This is a perturbation expansion method that uses n-alkanes as a reference system. It divides the conversions between property values and index values into three regions, applying a different equation in each region. For region 1: KVIS