Engine coolant (antifreeze) doesn't just keep the engine from freezing or overheating. It also contains corrosion inhibitors that protect the cooling system components from internal damage.
Coolant degrades over time. Most manufacturers recommend coolant flush and replacement every 5–7 years or 60,000–100,000 miles.
Skipping coolant maintenance leads to corrosion inside the radiator, water pump, and engine — eventual leaks, water pump failure, or radiator clog. Repair cost: $300–$1,500.
Color matters. Different vehicles use different coolant types (green, orange, yellow, pink) — they don't mix. Topping up with the wrong color causes gelling and damage.
Check coolant level monthly. Low coolant means a leak or evaporation — get it inspected.