This study examined the effects of dissolved oxygen on the corrosion properties of aluminum cast alloy, A384, in bio-ethanol blended gasoline fuel at 100 degrees C. Oxygen enhanced the corrosion resistance of the alloy by forming a protective hydrous oxide film. The acetic acid and water produced by ethanol oxidation in the fuel had a corrosive and protective effect, respectively. However, the protective hydrous oxide film enhanced by the water suppressed the corrosiveness of the acetic acid in the fuel when the two by-products coexisted. Therefore, the water formed by dissolved oxygen in the bio-ethanol blended gasoline fuel enhanced the corrosion resistance of the aluminum alloy by promoting the formation of a protective surface film. (C) 2010 Elsevier Ltd. All rights reserved.