In this paper, the static and dynamic performance characteristics of journal bearing in terms of load capacity, attitude angle, end leakage, frictional force, threshold speed and damped frequency are presented when the bearing operating under lubricants, which contain nanoparticles and viscosity of these lubricants varies with temperature. The nanoparticles used for the present work are copper oxide (CuO), cerium oxide ($CeO_2$) and aluminum oxide ($Al_2O_3$). Viscosity models for the lubricants are developed with the available experimental data. The modified Reynolds and energy equations are used to obtain pressure and temperature distribution across the lubricant film and these equations are solved by using the finite-element method and a direct iteration scheme. The static and dynamic performance characteristics of journal bearing are computed for various values of eccentricity ratios for isoviscous and thermoviscous lubricants. The computed results show that in isoviscous case, addition of nanoparticles does not change performance characteristics considerably but in thermoviscous case, changes are significant.