PURPOSE: To provide the subject concentrate suitable to liquid fuels in ordinary conditions or lubricant oils of a lubricating viscosity, in particular for lubricating oils for 2-cycle engines, formed by formulating an inactive solvent with a composition combining a respectively specific alkylphenol and aminophenol.

CONSTITUTION: This concentrate comprises 30 to 90 wt.pts. composition incorporating (A) an alkylphenol of formula I [R is a ≥10C aliphatic saturated hydrocarbon; Ar is an aromatic fraction of single-ring, condensed ring or linked polynuclear ring, having 0 to 3 optional substituent groups selected from lower alkyls or the like; (a), (b) are each an integer from 1 up to the triple of the number of aromatic nucleus in Ar] and (B) an aminophenol of formula II [(c) is the same as (a), provided that the total of (a)+(b)+(c) does not exceed the number of unsaturated valence of Ar], and (C) inactive solvent/diluent. The component (A) is advisable to be obtained by reacting a phenol with an olefin, the component (B) is obtained, for example, after allowing benzene to be stepwisely alkylated, nitrated, reduced and diazotized, by reacting the reaction product with water.