The new equation in this paper has its basis in quadratic mixing rules for non-random mixtures. Tests for the equation use the liquid kinematic viscosity of 232 binary mixtures and include comparison to three, commonly used equations in the literature. The new equation correlates the data within an absolute average percentage deviation of 0.33% compared to 0.52. 0.48 and 0.38% for the McAllister (MC). Dizechi-Marschall (DM), and Moumouzias-Ritzoulis (MR) equations, respectively. The new equation describes several ternary mixtures. (C) 2012 Elsevier B.V. All rights reserved.