Describes three test methods using the same apparatus for evaluating the oxidation stability of mineral insulating oils and of hydrocarbon-based insulating liquids. A method for evaluating the oxidation stability of unused uninhibited mineral insulating oils under accelerated conditions, a method for oils, a method for unused uninhibited and inhibited hydrocarbon insulating liquids. Replaces IEC 60074 (1963), IEC 60474 (1974) and IEC 60813 (1985). The contents of the corrigendum of September 1992 have been included in this copy.