The Mazda 3 is a sporty compact car that has been sold since 2004. Mazda recommends changing the coolant in your Mazda 3 at least every four years or 60,000 miles. Engine coolant should be bright green; if the coolant is discoloured, it may be time to change it. It doesn't matter if your Mazda 3 is equipped with the 2.0- or 2.3-litre engine--the procedure is the same.
Turn your engine off and allow it to cool completely. Wait at least 30 minutes prior to beginning the procedure.
Wrap a thick hand towel on the radiator cap and carefully twist it two to three times to relieve pressure. Step away from the vehicle for a few moments. Do not fully remove the cap.
Remove the plastic engine guard underneath the front part of the engine bay. The guard is attached by screws and bolts. Set the engine guard aside to access the bottom portion of the radiator.
Remove the engine coolant reservoir cap to assist the system in draining. Use a screwdriver to unscrew the radiator drain plug. Once the plug is unscrewed, pull on it to remove it. Allow the coolant to completely drain into the pan or container. This should take about 15 to 20 minutes.
Pour a gallon of distilled water through the coolant reservoir to clean out the system. Allow the water to drain into the pan with the coolant.
Replace the radiator drain plug and fill the system with coolant through the reservoir. The Mazda 3 coolant capacity is 7.9 qt., which is approximately 2 gallons. Do not overfill the coolant system. Tighten the radiator cap, but do not tighten the reservoir cap.
Reconnect the negative battery cable with the reservoir cap off. Start the engine and let it idle for a few minutes to rid the system of any possible air bubbles. Monitor your engine operating temperature while the engine is running. Turn the engine off, check for leaks, then replace the reservoir cap and the engine guard.
If your vehicle is used in severe driving conditions, such as excess heat, humidity or dust, replace your coolant every 30,000 miles. If you do not feel comfortable changing your own coolant, see your nearest Mazda dealer or certified mechanic.
Tap water contains minerals that may harm your cooling system. Do not use anything but distilled water. A gallon can be purchased at almost any grocery store. Do not use an engine coolant containing alcohol, methanol, borate or silicates. Your Mazda 3 has an aluminium engine, and these chemicals will damage it. Properly dispose of your engine coolant. It is against federal law to improperly dispose of engine coolant; it is highly toxic. Call (800) CLEAN-UP to find a waste facility near you (see Resources).