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Radiator Flush: Understanding the Benefits

Flushing your cooling system

When was the last time you changed the coolant? If at least two years have passed, then it may be time for a radiator flush. We’ll review how to flush your car’s radiator and take a look at the benefits of getting this job done.

Your Cooling System

Your vehicle’s cooling system is composed of a number of parts, including the radiator, thermostat, water pump, heater, engine oil cooler and various hoses, clamps and outlets. Today’s efficient engines contain numerous aluminum components and require superior corrosion protection to persevere. That’s where coolant comes in, typically offering a 50-50 blend of ethylene or propylene glycol and water.

The color of your coolant makes a difference too. Green and red coolant (also known as antifreeze) lasts about two years, while orange has a longer lifespan as it uses a different type of corrosion inhibitor. In any case, the takeaway is to never mix colors.

All coolant contains rust inhibitors, but when these elements quit working, the cooling passages found in your engine and radiator become susceptible to corrosion. Aged coolant can cause your engine to overheat with severe consequences, including a warped cylinder head along with camshafts, pistons and other critical parts damaged. Potentially, you’re looking at a complete engine replacement costing thousands of dollars with aged coolant setting this distressing scenario in motion.

Flush Your Radiator

Your owner’s manual outlines when a radiator flush should take place. In the meantime, check the cooling system when the engine is cold—never touch a hot radiator—only adding new coolant when required.


To perform a radiator flush, drain the old antifreeze completely. Always reference a shop manual for guidance. As for your tools, you’ll need a drain pan, shop towels, gloves and protective eyewear. Oil absorbent products can come in handy in the event of spills. Purchase radiator flush and a fill kit to expedite the process. The kit includes a cleaner and water solution designed to rid the cooling system of rust and corrosive deposits.

The third and final step involves filling the cooling system with the proper mix of coolant and water, ranging from 50 to 70 percent antifreeze, with the remainder composed of tap or distilled water. Use a funnel to add coolant, then use an antifreeze coolant tester to ensure a proper blend.

Some other tools needed, depending on the condition of your coolant system, includes new hoses, clamps, hose cutters, a screwdriver set, socket and ratchet sets and a new radiator cap if the old one has a worn gasket. Of course, only change hoses and clamps after removing the old coolant and before installing the new coolant.

Do Not Ignore

Flushing your cooling system is a relatively easy job, but it is also one that can just as easily be overlooked. Even if you have an older car with an engine composed mostly of high strength, low alloy steel and other materials, it needs adequate attention, something oil changes alone cannot provide.

Check out all the chemical products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on a radiator flush, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.

Matthew C. Keegan View All

Matt Keegan has maintained his love for cars ever since his father taught him kicking tires can be one way to uncover a problem with a vehicle’s suspension system. He since moved on to learn a few things about coefficient of drag, G-forces, toe-heel shifting, and how to work the crazy infotainment system in some random weekly driver. Matt is a member of the Washington Automotive Press Association and is a contributor to various print and online media sources.

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