Lubricants play a major role in mechanical machines and studies on various nanolubricants are reported in the literature. This work deals with nanolubricants using blend of oils as base for nanolubricants. Nano-blended lubricants were prepared with a blend of ISO VG46 oil (mineral oil) and Jatropha oil (non-edible vegetable oil) and using them in proportions of 90:10 and 80:20 by dispersing 0.5–3 wt.% of surface-modified CuO nanoparticles by a two-step method. Various properties of these oils such as dispersion stability, viscosity and thermal conductivity were determined. Experimental values of viscosity were compared with the values predicted by using different viscosity models. Nano-blended lubricant 9010 was found more sensitive at lower concentration of nanoparticles compared to nano-blended lubricant 8020. It is observed that nano-blended lubricant 9010 with 1.5 wt.% CuO is more suitable for use in place of ISO VG46 oil compared to nano-blended lubricant 8020. Thermal conductivity values of all types of nano-blended lubricants have been found by thermal conductivity model to be approximately matching with the measured values.