The anticorrosive effect of methanol extract of Tinospora cordifolia stem for Al and Cu metals in pure biodiesel and its 10% blend with petrodiesel was investigated at 25±2 °C in a closed system by corrosion, inhibition efficiency, adsorption, and electrochemical tests. The corrosion inhibiting action of the plant extract for Cu in the biodiesel was more efficient than in the blend, while the extract showed more anticorrosive behavior of Al metal in the blend than in the biodiesel. Adsorption of the plant extract on the metal surface conformed to the Langmuir adsorption model. The plant extract functioned as a mixed-type corrosion inhibitor for both the metals in both biodiesel and its blend based on the experimental results. Outcomes of the study confirm the suggestive evidence to formulate the green extract-based biodiesel additives to enhance the anti-corrosive response for the Al and Cu metal parts of the vehicle engine. Nepal-origin Tinospora cordifolia stem extract could be used as an anticorrosive agent to control the corrosion of Al and Cu metals in biodiesel-based fuels.