What is a Coolant Flush and Does my engine Need it?

The radiator fluid, commonly known as coolant or antifreeze, helps keep your engine cool when driving. Generally, if, for any reason, your car is short of coolant, your engine can overheat and eventually break down. But low-level coolant isn’t the only reason your vehicle might overheat.

You might have a coolant reach the fill line, but if it’s not in the right condition, you may as well damage your engine. Hence, there is a need for a coolant flush. Technically, one must choose between a coolant flush, which protects your engine, and high repair or engine replacement. But first, what is a coolant flush?

coolant flush near me

What is coolant flush?

A coolant flush is the process of getting rid of dirt, sludge, rust, and other contaminants from your vehicle’s cooling system.  The process involves removing all the coolant in the radiator and reservoir and replacing it with a fresh one. It’s worth noting that coolant flush is different from coolant change.

Coolant change focuses on just changing coolant, and not all old dirty coolant leaves the system before a new one is added. So here, some remnants of the old coolant would eventually contaminate the freshly added coolant. Coolant flush, however, ensures all the old dirty coolant leaves the system before a new one is added.

So dirt and sludge are eliminated from every part that stores and transports the coolant throughout the engine. A coolant flush also helps in checking the cooling system for signs or damages that can hinder engine performance.

Does my engine need a coolant flush?

Cars often have manufacturer-recommended intervals to change or to do a coolant flush. However, aside from sticking that, whether your car needs a coolant flush or not will depend on the coolant’s condition, or you may want to look out for other signs like bad coolant color.

If you regularly drive, especially during summer, you may need a coolant flush sooner than recommended, as coolant works more during this time. A drastic change in the color and consistency of the coolant may also indicate your engine needs a coolant flush. And an excellent way to know is to check the coolant once in a while

One of the most common signs you need a coolant flush is engine overheating.

Coolant generally helps keep the engine cool when running, so if it suddenly starts overheating, the fluid might be dirty and unable to work as intended. Is your engine’s heat indicator or thermometer up and causing the check engine light to turn? An overheating engine may trigger this. Hence, the need for a coolant flush.

You may also need a coolant flush if you have been driving your car for a long. The coolant, over time, may have accumulated dust and other debris that might reduce its working capacity. Even if it appears, it’s still working, flush it, as it’s only a matter of time before it starts acting abnormally.

Is coolant flush really necessary?

As coolant flows through your engine to cool it, it collects heat and other engine particles. Corrosion, rust, and other scales are also formed in the cooling system. All of which reduces the fluid efficiency over time.

With such a reduction, the coolant may not be able to keep the engine cool which often results in engine overheating and eventually lead to engine breakdown. A dirty radiator coolant can also cause corrosion in the radiator and also allow dirt into the engine.

So, is coolant flush necessary? Yes, coolant flush is necessary as it allows you to drive with not just a clean coolant but a clean cooling system. This means your engine will function well, stay clean, and last longer, invariably avoiding costly repairs or engine replacement.

How do you do coolant flush?

Opting for a coolant flush service gets your cooling system cleaned in no time since these professionals use a coolant flush machine. However, luxury comes with a price, so if you’re not ready to pay it, you may need to do it yourself.

All you need is to get the coolant flush kit and a radiator coolant for your specific vehicle. Other things you would need include:

  • Socket wrench
  • A large drain pan or bucket
  • Garden hose
  • Rag
  • Protective gloves
  • Protective glasses
  • Funnel

With everything in place, here is how to do a coolant flush:

  • Allow the engine to cool, as coolant can remain hot for up to hours after driving
  • Pop up the hood, open the reservoir and radiator cap to let out pressure, after which you close it properly
  • Jack up the front wheels of your car to have good access to the radiator drain plug. If you don’t know where the drain plug is, consult your owner’s manual
  • Check the condition of your radiator for rust and corrosion. Also, check the two hoses connecting the radiator to the engine for leaks, and brittle, and fix them before proceeding.
  • Place the drain pan under the drain plug and use the socket wrench to remove the drain plug bolt. Allow the old coolant to drain into the drain pan until the coolant starts dripping. Dispose of old fluid properly.
  • Open the radiator and pour the radiator coolant flush into the radiator and top with water to the fill line.
  • Replace the caps and run the engine for 10 minutes (always follow the coolant flush manufacturer’s instructions as the time to run the engine may differ)
  • Let the engine cool down, then drain the system again and flush once with water or possibly do this till only clean water is coming out from the drain valve.
  • Add your coolant with your funnel. Then let your car idle for 10 minutes so the coolant can circulate.
  • Let your car cool, then check the coolant level and top off if necessary.

What is the best engine coolant flush?

While there are several coolant flush brands in the market, not all will give a good clean. So here we have highlighted some of the best engine coolant flush.

Prestone Cooling system flush

Prestone Cooling System Flush

Prestone cooling system flush is one of the most versatile coolant flush on the market. And fortunately can be used both at home and in your vehicle, even in extreme conditions. It helps eliminate dirt, oil contamination, and buildup in your cooling system. This includes your radiator and other cooling systems.

Prestone excels in many areas, one of which is its toughness. No matter how hard rust and other scales are glued to the wall of your cooling system, Prestone got you. Hence, one of the best radiator flush for rust and other sediments. If you are using it specifically for cars, the Prestone cooling system flush comes in handy for all engines.

So whether you are using a diesel or petrol engine, it got you covered. It comes in various models and is best used with prestone coolant for extended engine life.

While this coolant flush has proven to be very effective, it comes with its rules. So be sure to follow the manufacturer’s instructions when using it.

For example, leaving it too long in your radiator could damage the cooling system or the engine. So, how long can radiator flush be left in the radiator? For prestone, it’s usually around a 40-45 minutes job. But your best bet is to follow the instructions that come with the coolant flush.

Blue Devil radiator flush

Blue Devil radiator flush

This radiator flush comes in handy in thoroughly eliminating grime and oil contamination of any sort, leaving you with a clean cooling system. This coolant flush helps give an extended vehicle life and a perfect cooling system. An outstanding feature of this product is that only a small amount is needed to do the flush.

With a quart, your radiator and entire cooling system will be cleaned of its sediments. However, while just a quart will do the job, getting a double wouldn’t hurt. And always remain that each manufacturer has its guidelines on how to use a radiator flush, so follow the instructions that come with it.

Royal purple coolant flush

Royal purple coolant flush

Royal purple is handy in removing gunk and heavy corrosion on your cooling. It is designed for virtually every type of car and will leave your cooling system totally clean.  The product is also known to extend the water pump lifespan.

A high point of this fluid is that unlike others with limited time for when the flush can stay, Royal purple can be left in the radiator for a whole day or more. Thanks to its non-corrosive nature. Royal purple comes as a two-in-one product—coolant and corrosion removal or as coolant flush.

If, however, you are going for the coolant flush, you will get a better working engine if you merge it with their coolant.  Lastly, remember to follow only this manufacturer’s instructions when using this product.

Liqui moly radiator cleaner

Liqui moly radiator cleaner

The liquid moly radiator cleaner is one of the best coolant flush for diesel engines and comes in handy in eliminating gunk and carbon deposits in your radiator. Generally, flushing doesn’t just keep the radiator clean; it also keeps other parts of your cooling system, such as water jackets, pumps, etc., clean.

Its cleaning efficiency is top-notch, that you will instantly notice an improvement in the engine’s performance. It also helps in the proper distribution of heat as well as reducing engine temperature by about 15°, hence, causing the engine to run at minimum temperature. The only drawback is it comes in small bottle quantities, so one will need a handful of it to get the job done.

Irontite thoro-flush radiator flush

Irontite Thoro-Flush
Image credit: Irontite

This radiator flush works practically for every cooling system and ensures all grime, sludge, and oil contamination is eliminated.  It immediately improves your vehicle performance by removing all rust, corrosion, and dirt from the system. If you have an old car, this flush is a perfect fit for restoring that old rusty radiator.

Another high point of this product is that, no matter how hard the build-up is, it removes them at ease. Now, that’s something to brag about. Thus making it one of the best radiator flush for sludge. Overall, this flush is result-oriented and satisfying and wields the strength of an industrial solution with exceptional performance.

Bar’s radiator flush

Bar's radiator flush

Many people want it done quickly, and Bar understands this. This radiator flush effectively removes sediments from your system in only ten minutes, restoring the cooling system and thus making it one of the fastest radiator cleaners you will see on the market. And aside from keeping the radiator clean, it also helps stop leaks.

Furthermore, it is built with an acid-free formula, making it easier to use. So even if you’re new to self-cleaning your radiator, it won’t harm you; try starting with this. However, while it helps clean all parts of the cooling system, it is known to be challenging to get it out of the radiator.

How to choose the best coolant flush

Great return on investment generally makes users happy. For this reason, you must ensure you get only what will work for your specific cars. Getting from a reliable brand is good, but if you don’t get what your car needs, you may have wasted your time and resources. So here is how to choose the best coolant flush for your car.

Get a notable brand.

Most Popular brands have been tested, so the chances of delivering just as promised are high. Here, we have highlighted some of the best coolant flush in the market.

Consider your engine type.

Select only one built for your engine type. Some coolant flush could go for both gasoline and diesel engines. On the other hand, some can only be used for diesel engines as they contain additives that can only care for diesel engines. So if you use diesel coolant flush for gasoline engines, you may not get the result promised by the manufacturer.

Works as promised

Some of the best coolants flush out there work as promised, so ensure you get one. This includes how fast it cleans, how long it can keep your engine working properly etc. An excellent place to get answers is to look through reviews; thousands of reviewers can’t tell lies. Try checking the best radiator flush forum for reviews.


Every coolant flush comes with specific instructions on how to use it. Especially if you’re new to the game, get one very easy to use. Bar’s radiator flush is a good example of an easy-to-use coolant.

How much does a coolant flush usually cost?

If you are ready to flush your coolant, the first thing will be to estimate how much you will be spending. So, how much does a coolant flush cost? Coolant flush can be anywhere between $50 and $150. The exact amount you will spend will, however, depend on several factors. First is the vehicle’s coolant capacity; the larger your vehicle, the more fluid you need.

Another factor that influences price is the price of the coolant flush, though some use only water. The last one is the person doing the flush. If you’re doing it yourself, you may have saved labor costs. All you need is to get the coolant, coolant flush, and coolant flush kit if needed.

Usually, mechanics can charge you up to $45 for labor alone since they utilize a coolant flush machine to make the process faster. Even professional charges differ. For example, the jiffy lube coolant flush cost is around $100, including car diagnosis, which differs from that of Pep Boys.

But ideally, you can compare different shops by typing coolant flush cost together with the firm you are inquiring about. For example, if you want to know the coolant flush cost at Walmart, search for “coolant flush cost Walmart.”


What happens if you don’t flush your coolant?

Not flushing your coolant will result in scales and rust particles building up in your cooling system over time. And if it stays long without flushing, these grime, sludge, and other contaminants may clog the transport channel and damage your heater core.

In other cases, dirt in your coolant and radiator will not allow the coolant to work as intended, leading to engine overheating and possible engine damage.  By the way, engine repairs and or replacement are possibly one of the most costly car issues to fix. Even if the engine has not packed up, performance may also be affected.

How often is a coolant flush needed?

Experts and mechanics give conflicting advice on when a flush is needed. Mostly, the age of your car, driving habits, and types of coolant should be considered. But Coolant flush, how often should you do it? Coolant flush is generally done every 30k miles or two years.

However, every car and coolant manufacturer has its recommended interval to do a coolant flush, so you may want to stick with it. If you drive regularly, you may need to flush sooner than expected; a smart way is checking always to know the condition of the fluid.

A coolant flush is also an avenue to check the cooling system for faults. Check the hoses running from the radiator to the thermostat and even the radiator cap. Change them if you see any sign of a tear or if you’ve used them for more than five years.

Can I flush my coolant myself?

You can carry out a coolant flush yourself. Just ensure you know your way around and get the necessary things needed. Here, a coolant flush kit, a coolant, and a coolant flush will be needed. Other things needed include a drain pan or bucket, socket wrench, rag, and protective gear for the eyes and hands.

How long does coolant flush take?

While deciding whether to do a coolant flush, a question that might pop up for many is how long does a coolant flush take? Coolant flush can take 30 minutes to 2 hours, depending on your approach.

A trained mechanic can do this in about 30 minutes since most car owners use a coolant flush machine. If, however, you’re doing it yourself, you may spend up to 2 hours. You may also need to allocate extra time for radiator inspection and fixing of coolant leaks.

Should I do a coolant flush or drain and fill?

It typically depends on what you want and your car’s condition. A coolant flush will get rid of all the old fluid and replace it with a fresh one; hence the whole system will run on clean fluid. Coolant flush also ensures that aside from having a clean coolant, the radiator and other parts of the cooling system are also free from debris, rust, or other contaminants.

If, however, you are draining and filling, some of the old fluid will still be left in the system. Draining cannot bring all out. This means the old fluid will later contaminate the new fluid and, therefore, still have dirt in the coolant and the entire cooling system. A coolant flush is, however, more expensive than coolant change.

How long should car coolant last?

The specific kind of coolant you use will determine how long it lasts in your car.  Manufacturers have theirs stated on the bottle. Some manufacturers say theirs should last for five years before requiring change. While for others, it could be seven years or more.

For example, there are water-based and non-water-based coolants, both with different prices, so each would have a different lifespan. Typically, there are no industry standards for how long coolant would last. So stick to your manufacturer-recommended coolant and how far that coolant can last.

Does coolant affect AC?

Coolant can affect AC, but not in the way many think. Generally, coolant in no way helps the AC unit to cool your cabin; another unit controls the AC. But here is what happens. If your coolant is low or too dirty, it may lose its effectiveness in keeping the engine cool, leading to engine overheating. That ultimately results in high temperatures under the hood.

Because your vehicle’s hood is close to the cabin, your car’s temperature will be affected, making the car hot. So, even while the AC is working, it will look like it is not functioning. So practically, coolant affects how an AC works by changing your cabin’s temperature, humidity, etc., due to engine overheating.

Is radiator fluid the same as coolant?

Yes, the radiator fluid is the same as coolant. Generally, as your coolant works to expel heat from the engine, it gets hot. In that condition, it will be less effective. When it gets too hot, the thermostat senses it, opens up, and allows cool coolant from the radiator to enter the engine while letting the hot fluid to flow into the radiator. The radiator then cools the fluid and sends it back to the engine to continue its work. So the fluid you see in your radiator is also the engine coolant.

Is coolant flush difficult?

Coolant flush is not difficult. You only need to know your way around and have the right tools. For instance, radiator coolant flush is usually recommended for doing the flush. If you let it stay in the radiator more than required, you risk damaging your cooling system and engine.

Therefore, while it’s not a difficult process, ensure you know what you are doing and always follow the manufacturer’s instructions. If it seems complicated, please take your vehicle to a professional mechanic to get your coolant flushed. By simply typing coolant flush near me, you should see a list of mechanics close to you.

Final Thoughts

Coolant flush is essential for keeping your cooling system clean and improving engine performance. Car owners should, therefore, include it in their routine maintenance. Purchase only coolant and coolant flush built for your specific engines and from a reliable brand. Else, you may end up damaging the engine meant to protect.

Prestone, Royal purple, ironite, etc., are some of the best coolant flush in the market. Lastly, you could stick to your manufacturer’s recommended interval or, better still, check the coolant’s condition for color change and smell. Some other signs indicating you need a coolant may include engine overheating, the heat indicator Light turning on the check engine light.

Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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