Most cars have aluminum pistons. This suggests aluminum and ethanol are not problematic together in the combustion chamber since ethanol has been used for decades in gasoline.
Ethanol is used in some aviation fuel applications, but not widely. Ethanol has lower energy density than petroleum aviation fuels and thus reduces range for a given fuel volume. Ethanol presents phase separation, vapor lock, and icing issues for airplanes due to altitude and cooling issues. Are there any issues of ethanol blocked for aviation usage due to chemical interactions with aluminum?
Copper is used in stills for alcohol production. Copper is directly contacted by the ethanol when making drinking alcohol. Stills have both copper and solder joints. Apparently stills must be cleaned on insides after several years due to sulfur compound buildup from products associated with the yeast production. Not having found copper corrosion problems from chemical contact with ethanol in stills, does anyone know of copper corrosion in stills due to ethanol contact?
Following up on the sulfur compound production on copper, there is a study of copper and steel corrosion rates related to fuel storage tanks with the metals in the presence of acid-producing bacteria. These studies found copper and steel corrosion rates of about one human hair thickness per year for metals in the headspace over a yeast extract including 5% ethanol by volume. This corrosion was associated with acetic acid produced by the microbes. See “Corrosion of copper and steel alloys in a simulated underground storage-tank sump environment containing acid-producing bacteria” by J. W. Sowards and E. Mansfield in Corrosion Science 2014, volume 87, pages 460-471.