Comparative Performance of Aqueous Propylene Glycol and Aqueous Ethylene Glycol Coolants

Propylene glycol (PG) based engine coolants have been tested in both heavy-duty and automotive service. Results of comparison tests between PG base engine coolants and traditional ethylene glycol (EG) base coolants are presented in this summary paper. The detailed testing program included laboratory testing for corrosion protection, freeze protection and heat transfer performance, engine testing for corrosion protection, low temperature performance and heat transfer, and extensive fleet testing in both automotive and heavy-duty applications. The testing has proven that PG is an excellent base fluid for modern engine coolants, providing the necessary heat transfer properties, freeze protection, boil-over protection and, when adequately inhibited, corrosion protection.