Why is a 50/50 solution of EG and distilled water optimal for antifreeze protection?

A 50/50 solution of ethylene glycol (EG) and distilled water is considered optimal for antifreeze protection primarily because it effectively balances both freezing and boiling points. Ethylene glycol has a high boiling point and low freezing point, allowing it to perform well across a range of temperatures.

When mixed with distilled water, the freezing point of the solution is significantly lowered compared to water alone, thus preventing the coolant from freezing in extremely low temperatures. Additionally, this mixture raises the boiling point above that of pure water, which helps prevent overheating in high-temperature conditions often encountered in engine operations. By maintaining this balance between freezing protection and boiling resistance, the mixture ensures that the engine coolant remains effective throughout varied operating conditions, thereby providing comprehensive engine protection.

Therefore, the 50/50 blend is essential for maintaining performance and preventing damage due to extreme temperatures in both cold and hot environments.