This work investigates the influence of the physicochemical characteristics of heavy (17.5 °API), medium (28.3 °API) and blend (50% heavy + 50% medium) crude petroleum on corrosion of AISI 1020 carbon steel at 25.0 ± 1.0°C. The corrosion resistance of steel was analyzed by electrochemical impedance spectroscopy, potentiodynamic polarization, and scanning electron microscopy. The electrochemical results and the micrographs show that the corrosion on steel surfaces after contact with the heavy oil is lesser than medium and blend petroleum, although the heavy oil presents a higher amount of total acid number, sulfur compounds and salt. On steel sample immersed in heavy oil, a localized pitting corrosion was identified, while on samples immersed in medium and blend petroleum was found evidence of pitting and alveolar corrosion.