The oxidation number only measures carbonyl groups (C=O). While esters contain carbonyl groups, one cannot calculate the percentage of ester in a PCMO formulation from the oxidation number unless the type of ester(s) are known as well as all other carbonyl containing components in the additives. There are scores of different esters available, and the esters I have seen used in motor oils range from 132 to 318 in the ratio of molecular weight to number of carbonyl groups.
A higher than typical oxidation number in motor oils likely indicates the use of ester base oils, especially if the marketer claims so, but the amount is just guess work.
A higher than typical oxidation number in motor oils likely indicates the use of ester base oils, especially if the marketer claims so, but the amount is just guess work.
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