Gasoline is a volatile liquid that is used in internal combustion engines. It is formed by a mixture of paraffins, naphthenes, olefins, and aromatic hydrocarbons (C 4 -C 12 ). During storage, the hydrocarbons present in gasoline react with atmospheric oxygen, and with each other, promoting changes in its physical and chemical properties, because of the formation of gums. These materials present macromolecular character and normally cause undesirable effects, such as deposits in filters and distribution lines. The present work evaluated the formation of gums in Brazilian gasoline added with different anhydrous ethyl alcohol and copper contents in the fuel. A discussion of the oxidation reaction mechanisms is also presented. The results show that the addition of anhydrous ethyl alcohol to gasoline does not contribute to the formation of gum in gasoline. It can be stated that the addition of anhydrous ethyl alcohol to gasoline provides benefits such as a reduction of gum deposits in an engine per liter of fuel consumed. Now, copper interferes significantly in the gum content of gasoline, because it is a catalyst of radicalar oxidation reactions and it accelerates peroxidation. Therefore, this metal must be avoided in any metal alloy that comes into contact with gasoline in the feeding system of engines.