Disclosed herein is a heat transfer fluid additive composition comprising: greater than or equal to 10 weight percent (wt %) of a carboxylic acid, based on the total weight of the composition; an azole compound; and a base, wherein the base is present in an amount sufficient to obtain a pH 8-10.5 when diluted by 50 volume % with water. The heat transfer fluid additive composition can be combined with other components to form a heat transfer fluid. The heat transfer fluid can be used in a heat transfer system.