What is the Best Radiator Flush in 2024?

If you are in a hurry and just want to find out what the best radiator flush is, then we recommend BlueDevil Radiator Flush as the best one.

Has your vehicle gone for more than three years or 30,000 miles without a radiator flush?

Or maybe the engine temperature warning light came on while you were driving?

If you answered yes to any of the previous questions, then you’d better hurry to perform a proper cooling system flush as it may be getting dirty in there!

And if left untreated, a dirty cooling system will cause overheating and result in serious (and very expensive) engine damage.

Read our radiator flush review to find out the best radiator cleaning solution to help you restore your vehicle cooling system to its optimum condition.

Here are the best radiator flushes we recommend:

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All of our reviews are based on extensive market research, expert input, and practical experience. We invest time and resources to analyze the products. This way, we can offer you genuine, accurate guides to help you get the best pick for your needs.

What is a Radiator Flush and Why do I Need One?

Radiator coolant, though fundamental, can build up unwanted contaminants and collect dirt and debris over time. This, if left untreated for too long, can cause radiator corrosion, generating rust, scaling, or other waste that you definitely do not want in your vehicle radiator or engine.

Rust and corrosion act as insulators and will result in suboptimal cooling, leaking, overheating, and eventually severe engine damage.

regular radiator flush is the solution. It’s basically a pressure washing for the vehicle cooling system. A flush forces several gallons of an ad hoc cleaner – aptly named radiator flush – through the cooling system to get rid of all the old antifreeze and the contaminants that may have built up in it.

Additional benefits of flushing your cooling system include removing the rust and scaling that has already built up on the radiator as a result of the old coolant, as well as lubricating and lengthening the life of your water pump. Furthermore, most coolant flush products have additives that can help prevent future leaks, foaming, corrosion and debris build-up.

Types of Radiator Flush

Radiator flushes come in mainly two forms: liquid and powder.

Liquid is the most common and tends to be the most effective, since it allows for the presence of useful additives that help corrode rust and reduce dirt and grime in the system. These solutions are simply poured in and flushed out, typically with water, to clean your clogged radiator.

Powder radiator flushing chemicals, on the other hand, are less common, but they can be very effective. The powder itself is highly concentrated and our heavy duty pick is, in fact, powder-based. However, the powder solutions need to be carefully diluted before using, creating an extra step for the user that could result in system damage if not performed properly.

How to Use Radiator Flush

Performing a radiator flush is definitely a doable DIY maintenance task.

Be sure to read and carefully follow the instructions on the label of the particular cleaning product you’re using. That’s critical. Failing to do so can result in ineffective cleaning or downright damage to the cooling system.

Here’s a great video showing the process step-by-step.

However, if you do go to a mechanic for your radiator flush rather than doing it yourself, take advantage of it and make sure he performs a full cooling system inspection to find any leaks in the system that may need fixing. Additionally, be sure to bring your own cleaner so you can be sure to be using the best radiator flush and the service charges will be lower.

How to choose the Best Radiator Flush

When selecting the best radiator flush for your needs, there are a couple of things you should consider.


First of all, read the label carefully. Not all radiator cleaning fluids will work for every vehicle. Some are specifically designed for particular kinds of radiators, like aluminum or brass.

Also, see if the cleaner has particular requirements regarding the coolant type and antifreeze.

The products we recommend are actually compatible with most vehicles on the market and can be mixed with all types of coolants and antifreeze. However, make sure to double-check the fluid before buying it to make sure you don’t pour an ill-suited cleaner into your vehicle.


Some coolant flushes are more concentrated than others. The more potent the solution is, the more cleaning power it will have, and the more effective it’ll be. This, however, can be a double-edged sword, because although a powerful clean is important, a too powerful solution can more easily damage the metal in your car if misused.

Ease of Use

Depending on the usage instructions of the particular product you selected, the steps you’ll have to perform could be more or less involved.

Generally speaking, liquid products are the most practical. The fluid is ready to use: you simply pour it in, let it stay for a bit, flush it out, and be done with it.

Powders, on the other hand, require more attention as you’ll have to precisely mix them with water. But they can sometime be more effective for particularly stubborn dirt residues.

So be sure to check the usage instructions before making a purchase, in order to select the radiator cleaner most appropriate for your needs and skills.

These are the Best Radiator Flushes

Alright, these are, in our experience and according to our in-depth review, the absolute best radiator flushes on the market.

Best Overall: BlueDevil Radiator Flush

BlueDevil Radiator Flush restores efficiency to vehicles by helping remove grease, rust, grime, and any other build-up that occurs during normal vehicle use.

The best radiator flush: BlueDevil Radiator Flush

The specially formulated coolant flush works extremely well in all vehicles, especially those with high mileage warranting a deep flush. Its advanced cleaning powers are designed to cut through the toughest of pollutants and contaminants.

It comes in a very practical 32-ounce bottle, which is enough to flush all sizes of cooling systems.

BlueDevil is a one-step product: all you have to do is pour it in and flush it out with water. It comes ready to use, so you don’t have to worry about diluting or mixing anything.

If you’re looking for a product which is worth your time and money, then you found it.

Best Radiator Flush for Rust: Thermocure Coolant System Rust Remover

Thermocure is a non-toxic and biodegradable formula by Evapo-Rust that’s designed for professional and personal use. Once flushed into the cooling system, this fluid removes rust deposits and scales from the radiator, water jackets, water pumps, engine blocks, and heads.

It contains no acids, bases, solvents, or other toxic ingredients, and it will not harm un-rusted steel or other metals, plastic, PVC, and most paints.

It restores the engine’s ability to transfer heat to the cooling system and consequently allows the engine to run cooler and last longer. One quart can treat up to a three-gallon tank.

If your car, truck, or tractor shows signs of rust or corrosion in the cooling system, definitely go with Thermocure. It is, without a doubt, the best radiator flush for rust in the cooling system.

Budget Pick: Prestone AS105 Radiator Flush and Cleaner

Prestone is a very well-known automotive brand. It produces high-quality products and its AS105 radiator flush and cleaner is no exception.

Its 2-in-1 formula is effective both for light flushing and heavy-duty cleaning of the cooling system, helping resolve and prevent overheat – which is one of the top causes of engine failure.

It’s also formulated to remove any scale and rust deposits that might have built up on your cooling system. With these deposits gone, coolant will flow unobstructed and heat transfer will be restored, so you’ll prevent overheating, breakdowns, and costly repairs.

Preston formula is free of toxins and acid, making it safe for all the metallic parts of your cooling system. It won’t cause corrosion or any form of damage to your cooling system. Also, it makes the product safer to use and easier to handle.

Given its very convenient price, the only reason this product didn’t rank higher in our review is because one bottle may not be enough to completely flush a dirty radiator. It may take a few times and more than one bottle to completely get the job done.

Best Heavy-Duty Radiator Flush: Irontite ThoroFlush

ThoroFlush is an all-in-one product for heavy-duty cleaning of the radiator and cooling system. Since this product comes in a concentrated powder, it lends itself to be mixed with various amounts of water to achieve different results.

It is one of the most powerful flushes available. However, as we said before, this is a double-edged sword: this product must be used with extreme caution. Be sure to carefully follow the product instructions to obtain the desired effect (and not damage the cooling system).

Irontite ThoroFlush is safe for use on cast iron, aluminum, brass and plastic components. Though more complex to use than our other recommendations, being so powerful it rightfully deserves a spot in our review.

FAQs about Radiator Flush

Can’t I just drain the radiator?

Simply draining the radiator may get rid of most of the old antifreeze but could leave some coolant and contaminants behind. These would then mix with and pollute your new antifreeze and may end up cause problems like overheating. You want to perform a full flush, to remove anything old and pave the way for new fluid.

Can’t I just use water to flush the radiator?

You absolutely can use just water to flush the system, but it is definitely not the best way to flush a radiator. Obviously, the cleaning action will be less effective and you will lose all of the benefits of using a proper flushing product. Considering the possible complications you can have from a dirty and rusty cooling system, we would definitely not recommend it. Prevention in this case, as with most things automotive, is way cheaper than cure.

How often should I flush my radiator?

As with all auto services and maintenance tasks, let your vehicle owner’s manual dictate how often you need a flush.
As a general rule, however, a coolant service is recommended about every 30,000 miles or three years, whichever comes first.

How much radiator flush should I use?

Read and carefully follow the instructions on the product label! Each product varies and will say on the packaging how much radiator cleaner is necessary to effectively flush the system. Dosage may also depend on your vehicle size and the capacity of the radiator.
A particularly dirty cooling system may need more than one application to be cleaned properly. So it’s always best to have more product than expected, as you never know when you’ll need that bit more to perform the flush.

How long should I leave in the radiator flush?

It will depend on the amount of dirt to remove and the strength of the solution. Typically, it is best to let a liquid solution sit in your system throughout the day as you drive your usual routes. Then, flushing the fluid should only take a few minutes. However, if you are using a more concentrated product like the IronTite, you will have to pay close attention to its instructions because leaving it in too long could cause damage. So be sure to always read and follow the product label carefully!

How do I know that the flush worked?

After you flushed your radiator with the cleaning solution, you should be able to tell if the new clean water you are pumping through the system is coming out clear or muddled. If it is clear, it is a sign that the flush worked and all the dirt was removed from the radiator. Otherwise, you may need to keep adding cleaning solution and flushing it out until there are no visible signs of debris.

Can a radiator flush cause problems?

Not using a radiator flush actually causes problems!
That said, improper use of radiator flush is generally the number one mistake most people make. It is wasteful and dangerous, and precisely why some people give a bad rep to coolant flushes, as they probably suffered damage from excessive dosage or misuse.
When applied properly and in the recommended dosage, a good radiator cleaning fluid is absolutely harmless for the vehicle. It will thoroughly clean the radiator and actually protect the cooling system from the inside.

Will a radiator flush help with overheating?

A radiator flush is the first thing you should do in case your vehicle shows signs of overheating!
Your radiator pumps coolant into your car’s engine, keeping it cool and preventing it from overheating. Without it, your engine would suffer and work much harder than it should. Radiator flush helps prevent debris from clogging your engine and rust from insulating the system and decreasing its efficiency.


Performing a cooling system flush regularly helps prevent rust, corrosion, and debris from causing problems to the engine, and keeps your vehicle running smoothly.

The best radiator flush from our review is BlueDevil Radiator Flush. It is the most effective, compatible, and easy-to-use coolant flush product on the market, and it has proved its worth again and again.

Buy it now to properly and thoroughly clean your vehicle cooling system.

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