How Often Should I get a Coolant Flush?

Brakes Plus Technician Auto Repair Automotive Services

When is the right time to change your engine coolant? The first place to check for what kind of coolant your vehicle should have installed, and therefore the coolant flush interval, is your vehicle’s owner’s manual.  For some vehicles, manufactures recommend changing the coolant every 30,000 miles.

For others, changing your coolant isn’t even mentioned on the maintenance schedule. If your vehicle owner’s manual does not specify a coolant flush interval, if it recommends replacing the thermostat or water pump, it is appropriate to flush the coolant during that maintenance item.

Coolant flushing interval is typically specified as 2 years or 30,000 miles for silicated coolants (typically green color) and 5 years or 100,000 miles for extended drain coolants (orange or gold in color).

Some manufacturers recommend you drain and flush the engine’s cooling system and change the coolant more often on vehicles subjected to heavy duty service driving, such as frequent towing, which can generate more heat.

Different coolants have different additives in them to inhibit corrosion based on the need of the system they are used in. The type of coolant and the additives present in your coolant will determine how often you should get a coolant flush.  There are many colors of coolant to choose from and each type has a different set of corrosion inhibitors present.

The main purpose of your cooling system is to keep your engine cool. The water jacket makes up the main part of your cooling system. It’s a space around your engine block and cylinder head, surrounding the cylinders and combustion chambers.  Your coolant’s secondary job is to make sure the components in your system corrode at a very slow rate. Cooling systems today can have copper, aluminum, cast iron, steel, and other metals present.  Flushing your coolant removes the particles and brown tint your coolant has acquired, but also replenishes the corrosion inhibitors that have worn out or broken down in your old coolant.

The coolant flowing through your water jacket pulls heat out of your engine and transfers it to the air / atmosphere around it. This transfer happens in your radiator, which is mounted at the front of your vehicle to take advantage of airflow as you drive. The water pump attaches to your engine and is usually driven by a belt. The water pump moves the coolant from your engine to your radiator. This process allows the heat to be transferred out of your engine, keeping it safe from excessive heat damage.

Your cooling system also includes the hoses connecting all the larger components, and the thermostat. The thermostat is a temperature-controlled valve that keeps your engine at a constant operating temperature.

Many systems also include a heater core to bring warm coolant into the cabin of your vehicle to heat it, a coolant reservoir to hold coolant as it expands and your system warms up, and the radiator cap which maintains the pressure in your system. When your vehicle is completely cold, remove the radiator cap and check the coolant level and condition.  You’ll probably find particles floating in your coolant, which will have a brownish tint.

Remember to wait until your vehicle is completely cold before removing the radiator cap. When the vehicle is hot, the coolant system is under pressure. Removing the cap can let loose a geyser of boiling coolant. So do not ever, under any circumstance, open a hot radiator system, even if the car is off. It will remain hot and pressurized for quite some time to come.

The small particles in your coolant can come from any of the many different components in your cooling system. Your engine block can corrode over time, so many particles could be small bits of cast iron and rust from inside the cooling jacket. The hoses that connect all the components are made from rubber, which can start to flake off as the hoses age. Your water pump will also wear out over time. The brown tint comes from all the different metals that make up your cooling system, slowing corroding over time.

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