The current ASTM (D5304) procedure for determining storage stability involves rather drastic conditions, namely, 16 hours at 90 C and under 100 psig of oxygen. These mandated test conditions give rise to the question, ''Does the reaction conditions induce chemical instability, or is it an accurate measure of the true instability process?'' Several organo-sulfur functional groups are known to be present in petroleum derived fuels. Thiophenes, benzothiophenes, sulfides, disulfides, and trace amounts of thiols are the organosulfur compounds most prevalent. The reaction of organosulfur compounds under the ASTM reaction conditions have not been investigated. The purpose of the present research is to determine if the ASTM reaction conditions induce a reaction in an otherwise stable fuel matrix.