The present study mainly reports the theoretical estimation of dynamic viscosities, eta, and kinematic viscosities, upsilon, for 150 binary liquid systems comprising different categories of organic compounds: alkanes, alcohols, aromatics, ketones, esters, and amines as well as some other typical organics containing O, N, and S atoms: acetonitrile, nitromethane, nitrobenzene, pyridine, 4-methylpyridine, dimethyl sulfoxide, and sulfolane. Computations were performed following two different approaches. The first methodology corresponded to correlative models of Grunberg-Nissan, Hind, Heric, Auslander, McAllister three-body and four-body equations as well as the Jouyban-Acree model. Fitting capabilities of simple polynomial equations and that of the Jouyban-Acree model for density and viscosity correlations were also tested for different degrees of polynomials. Accuracies of different models were analyzed by comparing values of sigma% as well as overall sigma% for different categories of binary systems investigated. Correlative models with a higher number of parameters can yield satisfactory results, the quality of correlations being dependent on the symmetry of model equations, molecular interactions, and the number of available data points also. On the other hand, the second methodology belongs to a predictive model: the UNIFAC-VISCO. Applicability of existing alpha(nm) parameters in predicting dynamic viscosities of the selected binary mixtures is tested by calculating the respective AAD%. The results for AAD% and OAAD% values suggest that the UNIFAC-VISCO model can yield very good results in predicting both the dynamic and kinematic viscosities of liquid mixtures. Finally, 34 pairs of new group-group interaction parameters, alpha(nm), of the UNIFAC-VISCO model were -determined with various amines, acetonitrile, nitromethane, nitrobenzene, pyridine, dimethyl sulfoxide, sulfolane, etc. as one of the components. The availability of these new group interaction parameters would contribute further in extending the range of applicability of the conventional UNIFAC-VISCO model, even to a wider range of multicomponent liquid systems.