Abstract: There are herein disclosed an additive for a lubricant or a fuel which comprises at least one selected from the group consisting of substituted hydroxyaromatic ester derivatives represented by the general formulae (I) and (II) ##STR1## wherein R.sup.1 to R.sup.5 are each an organic group having 6 or more carbon atoms, a, b, d, e, k and m are from 1 to 3, c, f, g, i and j are from 0 to 3, and h is from 0 to 4, but (f+g) is from 1 to 3, and (h+i) is from 1 to 6, an additive composition for a lubricant or a fuel, and a lubricating oil composition or a fuel composition containing the above-mentioned additive.The above-mentioned additive for the lubricant or the fuel is desirable as an ashless detergent excellent in high-temperature stability in place of a metal detergent, and the lubricating oil composition or the fuel composition containing this additive can suitably be used as the lubricant or the fuel for an internal combustion engine which can comply with future exhaust gas controls.

Abstract: Disclosed is a substance useful as a detergent-dispersant which has excellent stability at high temperatures and has an oxidation stability, a detergent-dispersant containing the same, a process of producing it, and fuel oil and lubricating oil composition comprising it.