EVALUATION OF MOTOR GASOLINE STABILITY.

Abstract : This report covers results of a storage program whose primary goal was the development of improved methods for evaluating motor gasoline stability. Several existing and potential predictive tests were applied to individual refinery components of gasoline, selected laboratory blends, and commercial gasolines for which ASTM D 525 induction periods ranged from 75 to 5000 minutes. Darkroom storage was conducted at 43 C, 54 C, and ambient temperatures, for various time periods with ambient storage ultimately reaching 4 years for most of the samples. Results confirm the findings of earlier researchers that ASTM D 525 is not viable as a predictive device by virtue of a low coefficient of determination between induction period and gun formed in storage at 43 C for periods up to 1 year. It is recognized, however, and ASTM D 525 is not likely to be abandoned as a specification stability test. Based upon the data generated under the four phases of this storage stability of commercial/military motor gasoline (produced for long term storage) is the ASTM D 873 Method using a 6- hour aging existent gum maximum limit of 5 mg/100 mL.