A Chemical Base for Engine Coolant / Antifreeze with Improved Thermal Stability Properties 2001-01-1182

Increasingly challenging international engine emissions reductions have resulted in some advances in engine emissions technologies that may motivate a change from the customary ethylene glycol and/or propylene glycol bases that have been the mainstay of engine antifreeze formulations for almost a century. The new engines' components, especially exhaust gas recirculation (EGR) devices, generate much greater thermal stress on the engine coolant. The oxidation of ethylene glycol and propylene glycol may be accelerated dramatically, resulting in coolant unsuitable for continued use in as little as a few months. The industry has been working towards extended engine coolant service intervals^1,2,3,4, with some recommendations for service extended to as long as five years. It follows, therefore, that a requirement for coolant change at four to six month intervals (due to accelerated oxidation & aging) would be unacceptable to vehicle owners.

Coolants are generally evaluated and judged by subjecting them to a series of physical properties and performance tests, and then comparing the data to the specifications published by ASTM⁵. This paper reports the data generated by subjecting a new coolant base chemistry, 1,3 Propanediol (PDO), to the ASTM D3306⁶ Light and Medium Duty (Automotive) and D6210/6211⁷ “Fully Formulated Engine Coolant” physical and performance testing protocols. These protocols qualify an engine coolant for use in virtually any engine cooling system, gasoline (petrol), diesel, and natural gas; engineered with or without wet sleeve cylinder liners.