Evaluation of boundary lubricants is crucial for enhancing the energy efficiency of a system, as the boundary lubrication (BL) regime involves direct asperity contact and exhibits the highest friction. Fatty acids are widely used as friction modifiers in BL regimes, forming tribofilms that reduce direct asperity contact and lower friction. This study examines the effect of molecular unsaturation on the frictional behaviour of oleic acids across temperatures. A Force-Controlled Pendulum Tribometer (FCPeT), which operates on energy dissipation methodology, was used to evaluate the frictional performance of a blend of oleic acid with base oil at temperatures of 27 °C, 60 °C, and 100 °C. The FCPeT quantifies friction by measuring energy dissipation during sliding. Results indicate that the coefficient of friction increases with temperature, rising from 0.10 at 27 °C to ~ 0.12 (steady state) at 100 °C. FTIR and XPS analyses of the wear track confirmed tribofilm formation. The XPS results reveal that at higher temperatures, tribofilm degrades, contributing to increased frictional dissipation. Graphical Abstract