Efforts have been made worldwide to find alternative fluids for industrial applications. Vegetable oil appears to be a perfect alternative, but using most of the vegetable oil as a feedstock made its use for industrial purposes challenging. The recent trend is to develop coolants/lubricants from non-edible seed oil. This work investigates the effects of zinc oxide nanoparticles on viscosity of transesterified neem oil. The crude neem oil was purified, transesterified and nanoparticles were dispersed in the transesterified oil at concentrations ranging from 0.0% to 1.0% at 0.2% intervals. Fourier Transform Infrared (FTIR) spectra were used to examine the structures of the samples and Scanning Electron Microscopy (SEM) analyses were used to examine the surface morphology of the samples. Viscosity were examined. Among other things, it was found that a small amount of ZnO (0.6%) nanoparticles in the oil could improve the viscosity of the fluid. The nanoliquid with a ZnO concentration of 0.6% appears to have optimal properties