Alkali treating of petroleum distillates is carried out to obtain the advantages of the product purity and to improve performance. The use and quality of alkaline solutions must be controlled since metal ions present as impurities can catalyze low temperature oxidation and polymerization of olefinic compounds; leading to formation of heavy emulsions which tend to deposit in hydrocarbon phases and eventually to block the handling systems. The effects of the variable factors “time, temperature, antioxidant and anticorrosion additives” were studied. The addition of a small amount of methanol was found to retard the deposit formation. This can be ascribed to ion-molecule reactions of methoxide ions with aryl and heavy thiols present in the light distillates. The promoting effects of light and the surrounding air on the stability of final treated product have been investigated.