This study investigates the impact of oil additives on the performance of hydrodynamic journal bearings using hazelnut oil. Various additives, including titanium dioxide, hexagonal boron nitride and graphite, are mixed with hazelnut oil in specific concentrations. Experimental tests are conducted in boundary and mixed lubrication regimes using a specialised rig to simulate bearing operating conditions. The friction performance of these oil‐additive combinations is evaluated in terms of bearing load, rotating speed and oil temperature. The findings contribute to understanding hazelnut oil as a potential lubricant and optimising its formulation for specific applications, promoting environmentally friendly lubricants and sustainability.