Disclosed is a method of simultaneously stabilizing an engine coolant concentrate and preventing hard water salt formation upon dilution of the coolant concentrate with hard water. The method comprises making a stabilized concentrate by adding to a coolant concentrate at least one stabilizer selected from the group consisting of polyacrylate polymers of the formula: where Rl is H; R4 is a terminating group; X is and R2 and R3 are each independently hydrogen, an alkali metal or an alkaline earth metal, and the sum of m and n provide a number average equivalent weight of less than 6500, and a number average molecular weight of less than 6500, the concentrate comprising 90 or more wt % freezing point depressant and then diluting the stabilized coolant concentrate with hard water to provide a final coolant composition.