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Why It's Important to Flush Your Vehicle's Cooling System

You may have often heard that you should flush your vehicle's cooling system, but haven't had it done recently – or at all. Don't let the importance of this piece of maintenance escape you. Fresh antifreeze benefits the engine by making it last longer and keeps the cooling system in good working order.

Antifreeze Lifespan

Antifreeze is not forever. Some types last longer than others; however, the green antifreeze typically found in older cars lasts for about two years or 48,000 miles. The anti-corrosion chemicals in the antifreeze break down and become ineffective after this time.

Organic Acid Technology (OAT) coolant, which is red, amber or orange, typically lasts for five years or up to 150,000 miles. This is the type of antifreeze typically found in newer vehicles, especially those with aluminum components. If the OAT antifreeze is heavy duty, you might squeeze another year out of it.

Once the anti-corrosion chemicals break down, the antifreeze no longer protects your engine's metal components from rusting. The engine may be made of many types of metals, including steel, solder, brass, copper, aluminum and cast iron. All of these metals corrode and deteriorate when exposed to water.

Engine Protection

Over time, you may have added plain water to your vehicle's radiator. This dilutes the antifreeze, but it will work in a pinch when the vehicle overheats while you are on the road. When the system contains more water than antifreeze, it will rust sooner rather than later; and then you'll have to start replacing components including the radiator, thermostat, freeze plugs, metal heater or water bypass lines and even the intake manifold. Thus, you should flush the system as soon as possible after adding water to the radiator.

Water passages run through the heads and other parts of the engine to keep the engine cool. They could rust though to other parts of the engine over years of using just water. Even a little bit of rust could break loose and run through the system, thus clogging the radiator and causing your vehicle to overheat. Metal heater and/or bypass pipes rust sooner than other parts of the engine. These may be located in places that are difficult to reach, thus costing you quite a bit of money to replace. A little preventative maintenance is easier on your pocket.

Maintenance Adds Up

It may seem like missing scheduled maintenance once or twice doesn't make a difference, but the changes to the engine are usually inside where you can't see them, including rust build-up in the water passages and metal hoses. Antifreeze inhibits rust; and more importantly, keeps the block from cracking during cold winters because it's freezing temperature is lower than that of just plain water. The freezing point of 50 percent antifreeze and 50 percent water is -34 degrees Fahrenheit and its boil over point is 265 degrees Fahrenheit. If you use 70 percent antifreeze, the boil freeze point is -84 degrees Fahrenheit and the boil over point is 276 degrees Fahrenheit.