The evaluation of the kinematic viscosity of shale oil binary blends is discussed. It is shown that the kinematic viscosity of shale oil originated light gas oil fraction, heavy gas oil fraction, commercial fuel oil and reduced shale oil blends can be evaluated by standard blending calculation technique, accepted for hydrocarbon oil blends. When the low viscosity component is the shale oil originated light "diesel oil" fraction, the experimental values of blend kinematic viscosity are always higher than calculated ones. For such blends difference between the logarithms of experimental and calculated values of kinematic viscosity can be described by a simple equation. Using this approach the binary blend kinematic viscosity can be evaluated with a great exactness.