Abstract: A process for manufacturing a lubricant additive for internal combustion engine fuel, especially for diesel fuel, in which the additive is derived, especially directly, from the esterification of acid oils, such acid oils are especially coming from the acidification of neutralization paste obtained via a process for refining, preferably a process for chemical refining, and especially a process for saponifying, one or more oils chosen from a plant oil and/or an animal oil, and the lubricant additive is more particularly intended for fuels with a low sulfur content, for example less than 500 ppm (weight).