What is the primary purpose of adding silicate to anti-freeze?

The primary purpose of adding silicate to anti-freeze is to protect aluminum components within the engine and cooling system. Many modern engines utilize aluminum parts due to their lightweight and good thermal conductivity. However, aluminum can be susceptible to corrosion and damage from various factors, including chemical reactions with the coolant. Silicate acts as a corrosion inhibitor, forming a protective layer on the surface of aluminum, thus preventing pitting and corrosion over time. This protection is essential for maintaining the longevity and efficiency of the engine components.

While there are other additives in anti-freeze for different reasons—like enhancing color to indicate the type of coolant, improving viscosity for better flow, or increasing the boiling point to prevent overheating—silicate's main and crucial role specifically targets the protection of aluminum surfaces in the engine.