An engine that is overheating will quickly self destruct. As a result, proper maintenance of the cooling system is very important.
So, The most important maintenance item is to flush and refill the coolant periodically.
So, Antifreeze has a number of additives that are designed to prevent corrosion in the cooling system. As a result, This corrosion tends to accelerate when several different types of metal interact with each other. The corrosion causes scale that eventually builds up and begins to clog the thin flat tubes in the radiator and heater core. As a result, causing the engine to eventually overheat.
The anti-corrosion chemicals in the antifreeze prevents this, but they have a limited life span. So, Newer antifreeze formulations will last for 5 years or 150,000 miles before requiring replacement. Most antifreeze used in vehicles however, is green in color and should be replaced every two years or 30,000 miles, whichever comes first.