The evaluation of the kinematic viscosity of shale oil originated distillate oil - residual petroleum oil binary blends is discussed It is shown that the kinematic viscosity of shale oil originated light "diesel oil" fraction and petroleum originated heavy fuel oil blends can be evaluated by the standard blending calculation technique. When the shale oil originated component is the light gas oil fraction, heavy gas oil fraction or commercial fuel oil, the experimental values of blend kinematic viscosity are always lower than the calculated ones. For such blends, a simple equation can be used for evaluation the difference between the experimental and calculated values of viscosity, depending on the component oil proportion and on the experimental values of viscosity.