Heat transfer fluids containing synergistic blends of corrosion inhibitor formulations

Corrosion inhibitor formulations for use in heat transfer fluids include: (a) an optionally substituted benzoic acid or a salt thereof; (b) at least a first n-alkyl monocarboxylic acid or a salt thereof and a second n-alkyl monocarboxylic acid or a salt thereof, the first n-alkyl monocarboxylic acid and the second n-alkyl monocarboxylic acid being different; and (c) an azole compound. A ratio of weight percent of the first n-alkyl monocarboxylic acid or the salt thereof to weight percent of the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:0.75 to about 1:2.00. A ratio of weight percent of the benzoic acid or the salt thereof to combined weight percent of the first n-alkyl monocarboxylic acid or the salt thereof and the second n-alkyl monocarboxylic acid or the salt thereof ranges from about 1:0.30 to about 1:2.25.