Why Do I Need a Coolant Flush?

A coolant flush is an important yet neglected service. Many people hold off on performing this service when recommended, but waiting or skipping can lead to big problems.

For the health and longevity of your coolant system, you need to complete a cooling system service at the recommended interval. Here’s what you need to know about your cooling system and coolant.

Why Is A Coolant System Service Important?

Cool change

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A coolant flush is just what it sounds like - the old coolant is flushed out of the engine's cooling system. The system is then replenished with a clean, new coolant. The flushing process removes all sorts of nastiness from your engine cooling system (rust, dirt, sludge, etc.). Removing these contaminants from the cooling system is important. These contaminants can build up in key areas of the cooling system, clogging the radiator, water hoses, water pump, and/or engine cooling passages. A clog in any of these areas can be very bad for your engine, as it will cause your engine to run hotter than it should.

But even if your coolant doesn't have any contaminants, it's important to understand that the coolant itself can wear down. Heat breaks down the coolant, reducing its effectiveness. Extreme temperatures can also reduce your coolant's life, as can exposure to the elements. As coolant begins to break down, you may notice a variety of problems:

  • Engine overheats or doesn't warm up very quickly in cold temperatures
  • Cooling system leaks
  • Poor performance with the interior heating system
  • Water pump failure, blown or damaged hoses, damaged radiator
  • In extreme cases, engine damage as a result of overheating

For a trouble-free cooling system, frequent service is vital.

How Coolant Works In The Cooling System


Coolant in your vehicle is made of a 50-50 mix of antifreeze and water. The cooling system is made of parts and fluid working together to control the temperature of the engine. The cooling system is a collection of passages inside the engine block and heads, a water pump, a thermostat, a radiator, and a bunch of hoses. The coolant runs through these parts and ensures the optimal engine operating temperatures.

As the coolant becomes contaminated and starts to break down over time and/or mileage, the cooling system loses effectiveness.

When A Coolant Flush Should Be Done

Pinpointing the exact mileage and time between cooling system services shouldn't be based on some book. The time can vary between vehicles, but more importantly, driving conditions. Severe driving conditions like:

  • Long periods of time spent idling (either parked or in traffic)
  • Frequent driving in stop and go conditions
  • Driving during very hot or cold weather
  • Towing, hauling, racing, or even spirited driving

can all put a strain on a cooling system. If your vehicle is driven in the severe conditions listed, make sure you're getting regular coolant system checks and maintenance.