Nitrites, a Common Coolant Additive.

Nitrites, a common coolant additive, can cause failure in Controlled Atmosphere Brazing (CAB) aluminum radiators due to a reaction with residual brazing flux on the aluminum surface. This reaction leads to increased corrosion, pitting, and potential engine failure. The CAB process leaves behind a brazing flux that reacts with nitrites in the coolant, oxidizing the aluminum and increasing corrosion rates. 

Nitrate-free antifreeze, also known as nitrite-free antifreeze or Extended Life Coolant (ELC) coolant, is a type of coolant that uses organic acid technology (OAT) to prevent corrosion and scale buildup in cooling systems. It is formulated without nitrites, which were traditionally used as corrosion inhibitors but are now considered less effective in modern, higher-temperature engines. 

Traditional Coolants vs. Nitrate-Free Coolants: 

Traditional coolants:

Often used nitrites as a key corrosion inhibitor, but these nitrites can degrade at higher temperatures, leading to less effective protection in modern engines. 

Nitrate-free coolants (ELC):

Utilize organic acid technology (OAT) and more stable corrosion inhibitors like molybdate. They offer extended protection against corrosion, scale, and other issues, while also being compatible with a wider range of metals, including aluminum. 

Benefits of Nitrate-Free Antifreeze: 

Extended Protection:

Nitrite-free coolants provide longer-lasting protection against corrosion and other damage to cooling system components. 

Compatibility:

They are generally backward compatible with older cooling systems and can be used in both diesel and gasoline engines. 

Reduced Maintenance:

Due to their extended life and stability, nitrate-free coolants often require less frequent maintenance, such as coolant changes or additive additions. 

Protection of Aluminum Components:

Many ELC formulas are designed to protect aluminum components, which are common in modern engine designs. 

When to Consider Nitrate-Free Antifreeze:

Modern, High-Performance Engines:

Nitrite-free coolants are often recommended for use in modern engines, especially those that operate at higher temperatures or use aluminum components. 

Heavy-Duty Applications:

They are commonly used in heavy-duty applications like trucks and industrial equipment where extended life and reliable protection are crucial. 

OEM Recommendations:

Many engine manufacturers recommend or require the use of nitrite-free coolants for specific engine models or applications.