Dynamic stiffness and damping coefficients of a finite journal bearing operating on TiO2 based nanolubricant are obtained using the linear perturbation approach. Time dependent version of governing Reynolds equation is modified to consider the couple stress effect of TiO2 nanoparticle lubricant additives. The viscosity variation of lubricant with varying concentrations of nanoparticle additives is simulated using a modified Krieger-Dougherty model. The modified Reynolds equation is solved using linear perturbation approach to obtain the dynamic pressures and dynamic coefficients. Threshold stability maps are plotted depicting stable operating regions of journal bearing operating on TiO2 nanolubricants. Results reveal an increase in stiffness and damping coefficients, and a corresponding improvement in whirl instability characteristics of journal bearings, with increase in TiO2 nanoparticle concentration.