In this work, we have studied the effect of titanium(lV) oxide (TiO2) nanoparticles dispersed in an engine lubricant oil on its rheological behavior. In order to prepare this nanofluid, mechanical stirrer and ultrasonic bathwere used. The nanoparticles were characterized using SEM, TEMand dynamic light scanning. The rheological behavior of the system was studied by a parallel plate rheometer. Then, oleic acid, as surfactant, was used to stabilize suspensions. Also, the effect of the surfactant on the rheological behavior was studied. Three different models for rheological behavior, namely Power law, Cross and Carreaumodels,were considered. The Carreaumodel provides the best prediction of the rheological behavior for this system.
