Abstract: A test substrate for determining concentration of an organic corrosion inhibitor in a coolant fluid is provided. The test substrate comprises a porous substrate having at least a surface treated with a sufficient amount of at least a metal salt for reacting with a molar equivalent amount of the organic corrosion inhibitor in a representative sample of the coolant fluid, and at least a color indicator. The color indicator reacts with the metal salt and/or the organic corrosion inhibitor, forming an irreversibly colored complex and causing a color change in the test substrate.

Abstract: The invention includes, in one embodiment, a method for determining the presence or absence of a corrosion-inhibitory level of carboxylate anion in used engine coolant which includes: obtaining a known quantity of the engine coolant as a representative sample thereof, the sample containing a level of carboxylate anion to be determined; adding a fixed quantity of an aluminum containing color indicator to the sample, where the color of the aluminum color indicator is different from the original color of the sample, thereby changing the color of the sample to substantially the color of the aluminum color indicator, where at least a portion of the aluminum color indicator complexes with at least a portion of the carboxylate anion to form a colored insoluble aluminum-carboxylate complex, where the colored insoluble aluminum-carboxylate complex precipitates, and where the color of the sample remains substantially the color of the aluminum color indicator when the level of carboxylate anion therein is below an effec

Abstract: The present invention comprises an improved antifreeze coolant composition with certain additives that serve to increase the thermal stability of the glycol component of a glycol/water coolant composition and to reduce the tendency of the glycol component to degrade under elevated thermal conditions. These additives comprise organic compounds with a carboxylic acid moiety and a hydroxyl moiety, and also tricarballylic acid. Another aspect of this invention concerns a method for improving the stability of the glycol component of a glycol/water coolant composition in engine cooling/heating systems by formulating a glycol/water coolant composition with the thermal stability additive to form an improved coolant composition, and contacting the engine cooling/heating system with the improved coolant composition.

Abstract: The present invention comprises an improved antifreeze coolant composition with certain additives that serve to increase the thermal stability of the glycol component of a glycol/water coolant composition and to reduce the tendency of the glycol component to degrade under elevated thermal conditions. These additives comprise organic compounds with a carboxylic acid moiety and a hydroxyl moiety, and also tricarballylic acid. Another aspect of this invention concerns a method for improving the stability of the glycol component of a glycol/water coolant composition in engine cooling/heating systems by formulating a glycol/water coolant composition with the thermal stability additive to form an improved coolant composition, and contacting the engine cooling/heating system with the improved coolant composition.