In the current study, two viscosity models, namely, the modified Yarranton-Satyro correlation (MYS) and the free volume theory (FVT) coupled with the SAFT+cubic EoS, have been implemented for correlation and prediction of data of about 20 pure compounds and their binary mixtures. A representative selection of nearly 4000 experimental points covering a large part of the available elevated pressure data has been considered. It has been demonstrated that MYS is characterized by superior predictive potential and exhibits higher overall accuracy. Nevertheless, this approach still does not completely address a fundamental problem of predicting viscosities in the entire PVT range without relying on experimental data.