The objective of this experimental investigation is to assess the variations of thermal conductivity and viscosity of liquid paraffin-Al₂O₃ nanofluid containing oleic acid surfactant against temperature, nanoparticle mass concentration and surfactant concentration. The experiments are performed in the temperature range of 20–50 °C, nanoparticle mass concentration range of 1–5%, and surfactant/nanoparticle mass ratio of 1:3, 2:3 and 3:3. The results showed that the nanofluid behaves as a shear thinning fluid. Besides, it was found that boosting the nanoparticle concentration causes an increase in the thermal conductivity and viscosity, while augmenting the temperature results in a decrease in the viscosity and an increase in the thermal conductivity. Moreover, it was observed that the viscosity increases with surfactant concentration, while the thermal conductivity initially rises with surfactant concentration and then …