In this study, the two-parameter van der Waals type cubic equations of state (EOS) of Redlich-Kwong (RK), Soave-Redlich-Kwong (SRK), Peng-Robison (PR), and Peng-Robinson-Strjek-Vera (PRSV) were used with the frying kinematic viscosity model to estimate the viscosities of 31 nonaqueous binary mixtures. The frying's excess activation free energy of flow was related to the excess Gibbs free energy of mixture and calculated by the EOS in this study. The effect of the molecular interaction parameters and the mixing rule, van der Waals (vdW), van Laar (vL) and Redlich-Kister (RK) on the viscosity estimations were also considered. The computation results show that, the molecular interaction parameter affects viscosity estimation more than EOS and mixing rules do. It is observed that the viscosity estimations with interaction parameter correlated from the excess volume of mixtures are much better than that from the densities of mixtures. The percentage average absolute deviations (AAD(%)) for the former are <1% (with some exceptions given in the later paragraph) and that for the latter case are <3% (with some exceptions also given in the later paragraph). It is also interesting to observe that these four EOS are suitable to estimate the viscosities of the present binary mixtures and that none of these four EOS is obviously superior to others if the interaction parameters were from the correlation of excess volumes of mixtures. More observations were discussed in the section of computation results and discussion.