What are coolant system additives? A coolant system additive is a fluid added to a coolant to provide additional protection against rust, corrosion, and erosion. Coolant additives also help efficiently absorb and transfer heat from the engine.
Are coolant system additives already in my antifreeze/coolant fluid? There are small amounts of additives that are already in your antifreeze/coolants to protect the engine lining from corrosion.