Coolant is a working fluid, not a fill-and-forget one. Besides lowering the freezing point and raising the boiling point, it carries corrosion inhibitors that protect the radiator, water pump, heater core, and the metal passages inside the engine. Those additives are consumed over time, and as they're used up the coolant can turn acidic and start working against the very parts it's meant to protect.
A coolant flush and exchange removes the old, depleted fluid and replaces it with fresh coolant of the correct type, restoring its heat-transfer and anti-corrosion protection. It's interval maintenance — done on schedule rather than in response to a failure — and it's one of the least expensive things you can do to extend the life of the cooling system. At New Concept, we use the coolant your vehicle calls for and check the condition of the system while we're in it.