FIELD: corrosion protection. SUBSTANCE: invention relates to organic acidic corrosion inhibitors for use in antifreezing cooling compositions and concentrates. Composition contains mixture of C8-monocarboxylic acid or its isomer, or salt, or their mixtures with neodecanoic acid or its isomer, or salt, or their mixtures, total concentration of monocarboxylic acid ranging from about 2.0 to about 5.0 wt %. Composition contains water (ca. 10 to 90 wt %) and antifreezing cooling concentrate containing liquid alcohol functioning as depressant lowering freezing point and corrosion-inhibiting composition. C8-Monocarboxylic acid and neodecanoic acid can be present in corrosion-inhibiting composition at weight ratio 3:1. Invention also provides method for inhibiting corrosion of metals in internal combustion engines including step, in which metal is in contact with antifreezing cooling composition. Antifreezing cooling concentrate can contain 90-98 % liquid alcohol, 2.0-5.0% mixture of 2- ethylhexanoic and neodecanoic acids, 0.5% tolyltiazole, and alkali metal hydroxide in amount large enough to change pH from 6.9 to 9.6. EFFECT: prolonged corrosion protection in internal combustion engines compared to conventional inhibitors or those containing only C8-monocarboxylic component. 26 cl, 1 dwg, 4 tbl, 26 ex
