Top 6 Best Radiator Flushes and Cleaners [2021]

Good engine cooling in your vehicle ensures smooth operation and avoids costly and unexpected breakdowns associated with engine overheating. A properly maintained radiator will allow your car to run smoothly, avoid overheating, and could prevent the engine from serious breakdowns.

In this article, we are going to suggest the 6 best radiator flushes that you may need when cleaning your car’s radiator. There are other popular brands of radiator flushes like Royal Purple Flush and Irontite Thoroflush but due to high demand, these products are always out of stock. The following list of radiator flushes are excellent alternatives.

What is radiator flush?

A radiator flush is a liquid product designed and manufactured to clean radiators. Radiator coolant needs to be flushed because it develops residue over the years and it needs a special solution like radiator flush to clean and drain everything that is developed inside your radiator over the years. Dirt and rust particles including other foreign materials are either floating or sticking inside the coolant which can clog your radiator or heater core. In order to remove all of these materials, you need to flush and drain your radiator using a radiator flush.

  • Best
    Value

    Prestone AS107 / AS105 Super Radiator Flush

    Prestone AS107 / AS105 Super Radiator Flush

    4.4

    97 reviews

    Check price

  • Editors
    Choice

    Gunk Motor Medic

    Gunk Motor Medic

    4.4

    92 reviews

    Check price

  • PrimoChill Rad Clean

    PrimoChill Rad Clean

    4.8

    66 reviews

    Check price

  • Hy-Per Lube HFL400-4PK

    Hy-Per Lube HFL400-4PK

    5.0

    6 reviews

    Check price

  • Liqui Moly 2051 Radiator Cleaners

    Liqui Moly 2051 Radiator Cleaners

    5.0

    1 rating reviews

    Check price

Prestone AS107 / AS105 Super Radiator Flush Gunk Motor Medic PrimoChill Rad Clean Hy-Per Lube HFL400-4PK Liqui Moly 2051 Radiator Cleaners

Best
Value

Prestone AS107 / AS105 Super Radiator Flush

Editors
Choice

Gunk Motor Medic

PrimoChill Rad Clean
Hy-Per Lube HFL400-4PK
Liqui Moly 2051 Radiator Cleaners
4.4

97 reviews

4.4

92 reviews

4.8

66 reviews

5.0

6 reviews

5.0

1 rating reviews

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Prestone AS107 / AS105 Super Radiator Flush

Prestone AS107 / AS105 Super Radiator Flush

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  • PROS

    • Excellent reviews, effective and solid solution

    • Remove rust deposits and oily residue

    • Helps maximize cooling system efficiency

    • Intended for cars with heavier build ups of rust and radiator and heater core deposits

  • CONS

    • Don’t leave it in the system for too long

4.4

97 reviews

Check price

Prestone is a brand that should be familiar with all DIY mechanics and shade trees. This 2-in-1 formula is designed for intensive washing and cleaning of a cooling system, with the goal of preventing future overheating calamities.

The Prestone radiator flush featured here is offered in 650ml. If you have a horrible car, it’s probably a good idea to buy the bulk package. Prestone says it effectively removes heavy deposits by incorporating metal oxides into the solution, avoiding the hilarity of the rad cap.

A premium Prestone antifreeze/coolant change begins with Prestone Super Radiator Flush. Helps remove rust deposits and oily residue in an easy, one-step process. The premium formulation helps maximize cooling system efficiency. This Super Radiator Flush maximizes cooling system efficiency by helping to flush out harmful rust deposits, grease, and oily residue. It uses a strong chelating compound to bind rust and other corrosion deposits to help flush them out of the system prior to installing new antifreeze. Detergents emulsify oily residues. The Prestone radiator flush is intended for cars with heavier build-ups of rust and radiator and heater core deposits.

Gunk Motor Medic

Gunk Motor Medic

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  • PROS

    • American brand backed by a great company

    • Considerably cheap

    • Compatible with all cooling systems

  • CONS

    • You know it will probably take more than 10 minutes

4.4

92 reviews

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The radiator Gunk flush you see here is part of the Gunk family of products, but it doesn’t use their name as the main attraction. Claiming to be a 10-minute fix, it is said to quickly remove grease, dirt, rust, and scale from your miserable car radiator.

Containing no acids, the discharge must be compatible with all cooling systems (we’re looking at it here, DexCool) without the need for a separate neutralizing solution. The review covers at least the last three years, and only scattered airheads say they “didn’t notice anything” after applying the treatment.

PrimoChill Rad Clean

PrimoChill Rad Clean

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  • PROS

    • 5 star Amazon rating and considered one of the most effective radiator flushes

    • Environmentally friendly, no toxic, and requires no protective equipment to use

    • Reasonably affordable

  • CONS

    • Not compatible with aluminum radiators

4.8

66 reviews

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The PrimoChill Rad Clean – Radiator Cleaning Treatment is a solution for cleaning radiators outside of a loop. By using this cleaner you can “scrub” the inside of your rad without fear of damaging other components, seals, or acrylic! This solution is easy to mix, easy to use, and gets you ready to go!

Considered one of the most effective radiator flushes, it features water-based and environmentally responsible solutions, safe and non-toxic. You don’t need special protective equipment to use this solution. Dosage: Mix 1/2 bottle with 32oz of DI or distilled water. Compatibility: Rad Clean is compatible with the internal metals found in radiators only!

Hy-Per Lube HFL400-4PK

Hy-Per Lube HFL400-4PK

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  • PROS

    • Eliminates Damaging Coolant Gels

    • Reduces Operating Temperatures

    • Neutralizes Acids That Cause Corrosion

    • Helps Prevent Formation of Scales / Deposits

  • CONS

    • A bit pricey compared to other leading brands

5.0

6 reviews

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Hy-per Lube Super Flush removes coolant gels and neutralizes acids in the cooling system. It cleans the entire cooling system preventing overheating and corrosion. High-Performance Hyper Super Flush cleans better than the leading brand. The environmentally safe formula can be safely flushed to drain with no environmental concerns.

A proud American brand, Hy-Perlube radiator flush and cleaner is one of the most effective and one of the best radiator coolant additive cleaners available on the market today proved by the 5-star Amazon reviews given by happy customers.

Whether you have a plastic or aluminum radiator, Hy-Per lube is compatible and would not damage the internal cooling system. Furthermore, it is non-toxic, environmentally friendly, and does not need any personal protective equipment like gloves to use.

Liqui Moly 2051 Radiator Cleaners

Liqui Moly 2051 Radiator Cleaners

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  • PROS

    • Trusted automotive brand

    • Market leader in Europe

    • Tested and proven product compatible with plastic and aluminum radiators

  • CONS

    • Bottle units in metric that North Americans may find difficult to understand

5.0

1 rating reviews

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As a brand familiar to anyone who has spent time watching episodes of Australian Supercars or Mighty Car Mods, it’s easy to mistake Liqui Moly for a company with roots in Australia. In fact, it’s a German brand, you know, those same people who are notoriously as picky about their ADAC tests as they are about their beer.

Your radiator also discharges, if online reviews are any indication. Save for a couple of jokers who seemed to give a star or two for no reason, customers confirm that this removes deposits containing oil and lime, ensuring the engine runs reliably and at optimum temperature. Bonus: it does not contain aggressive acids or alkalis.

Liqui Moly is a very popular and trusted German brand of automotive products motor oils, additives, car care, service products and one of the best radiator flushes on the market today.

CLR PRO Radiator Flush and Cleaner

CLR PRO Radiator Flush and Cleaner

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  • PROS

    • Heavy-duty designed for all types of radiators

    • Economical if you are a mechanic and cleans a lot of fo radiators

  • CONS

    • Not advisable for DIY due to volume packaging

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When talking about one of the best radiator coolant additive cleaners, look no other than the CLR POR. The Heavy Duty Radiator Flush and Cleaner is designed for high mileage vehicles to remove heavy scale buildup and rust in radiators and heater cores. It removes 10x more scale than the leading brand; CLR PRO Heavy Duty Radiator Flush and Cleaner is free of ammonia, alcohol, and phosphate. With an average 3 gallon radiator, CLR PRO Flush and Cleaner remove more scale in 10 minutes than competitive products do in 30 minutes; perfect for car maintenance kits.

Questions about radiator and cooling system

What is the cooling circuit?

The cooling circuit is in charge of maintaining the optimum temperature in the engine to guarantee its proper functioning. In general, modern cars use a cooling system using a special fluid that allows cooling to maintain the temperature between 80ºC and 95ºC, depending on the models.

The radiator is one of the most important parts of this circuit, together with the water pump, the thermostat, the hoses, the fan, and the coolant reservoir. Its discovery and further development are some of the great advances in the automotive industry by allowing prolonged use of the engine without it overheating.

The importance of radiators

Its operation is based on a series of parallel tubes through which the coolant circulates, all within a heatsink located on the front of the vehicle. This design allows the entry of air from outside and serves to regulate the temperature in the refrigeration circuit. The most used materials are aluminum and copper, depending on the brand and model. There are also some radiators that use a special oil as the cooling fluid.

When the temperature in the engine exceeds 70ºC, the thermostat is activated, and with it, the coolant begins to circulate, which comes into contact with the engine water and cools it. The maximum supported by the refrigerant fluid is approximately 95ºC. Once this temperature has been reached, the fan is activated, which contributes to its reduction, maintaining optimal conditions for engine operation (about 90ºC).

Radiator cleaning and maintenance

Such an important part requires special care and periodic inspection to avoid overheating of the engine that could lead to serious breakdowns. The most important thing, when you go to check its condition, is that the engine is cold. As soon as you open the hood, you can perform a superficial cleaning of the heatsink with the help of a bristle brush. If you do this regularly you will save yourself having to disassemble it.

In addition to this, its drainage is recommended approximately every two years. Doing it is very easy. Just place a container under the drain valve and let all the coolant runoff. Remember that it is toxic, so you should avoid coming into direct contact with it. This is a good time to check that all hoses and pipes are in good condition and that there are no leaks. After running water through the circuit and removing debris, you can refill the tank with a mixture of distilled water and coolant. Start the engine and let the radiator eliminate the air from the circuit

The car radiator and its breakdowns

The engine cooling radiator was invented by Wilhelm Maybach in 1897 and was improved by Samuel Brown, who greatly increased its cooling capacity.

In general, this component consists of a coil of metal tubes through which the hot coolant from the engine circulates. Thanks to the air generated by the fan, this circuit is cooled and the liquid leaves the radiator at the right temperature to be recirculated through the engine.

A common fault that makes it necessary to repair the cooling radiator of the car immediately is the loss of coolant due to a leak in the circuit. This can cause an alteration in the cooling cycle of the engine, and an overheating in this could cause very serious failures, both in the engine itself and in other components of the vehicle that depend on it.

Special attention must be paid when the warning light (or other indication in text format) on the instrument panel warns that the antifreeze level is not correct. In addition, it is essential to observe the remains of this liquid that the vehicle may leave on the ground, as they can guide the approximate position of the leak. These evacuations should not be confused with the expulsion of condensed (colorless) water, coming from the air conditioning, or oil.

Steps to repair a car radiator

Here are the basic steps to repair a car radiator when there is a leak. Remember that radiator flushing is needed before doing any of the following repair procedures. Failure to flush cooling system will only worsen the problem.

  • Locate the source of the leak. Before diagnosing the radiator leak, it is recommended to check both the coolant reservoir (which could have a crack) and its cap (which could have rusted, deformed, or worn and acquired slack).
  • The leak may exist due to cracks or micro-tears in the connecting hoses of the radiator itself or because the clamps of these hoses have been able to loosen.
  • If it is found to be in the radiator, you must proceed to locate its origin. To do this, you have to start the engine, wait for it to take up the temperature, and find at which point a bubble appears, from which liquid of a striking color overflows.
  • The liquid is under pressure in the circuit, so it could be projected if the leak hole is large. Therefore, it is essential that the workshop technician use the necessary protections to repair a car radiator.
  • For an easy location of the leak, it is recommended that the radiator does not have accumulated dirt (neither on the outside nor on the inside). If you have it, it is advisable to clean it well with a quality product. Drain the radiator. With the engine completely cold, the drain valve (located at the bottom of the radiator) must be opened to drain the coolant.
  • Complete emptying of the circuit must be ensured. To do this, it is advisable to fill the tank with distilled water or antifreeze and start the vehicle for a few minutes without this liquid getting hot. In this way, the water is forced to recirculate and, thus, the remains of old refrigerant are dragged towards the discharge valve. This step can be repeated several times until the bowel movement is clean.
  • Prepare the surface to be repaired. Abrasive cleaning must be carried out in the area to be intervened to rid it of possible traces of rust and corrosion. This facilitates the adhesion of the coating product.
  • After cleaning the area, blow off any metal debris that may have stuck to the radiator and degrease and clean the surface. For this, it is recommended to use suitable products for this purpose, such as LOCTITE SF 7063 and TEROSON VR 10.
  • When cleaning the car’s cooling radiator from the outside, pay special attention to the pressure with which it is cleaned, since there is a risk of bending the cooling fins of the coil, which would influence the dissipation capacity of radiator heat. In addition, the electrical connections of different components must be properly sealed if they cannot be moved away from the radiator.
  • Assessment of the damage and repair of the leak.

    The deposition of residues present in the coolant can cause internal obstruction of the tubes. Although sometimes this accumulated dirt can be descaled, other times its cleaning is not possible and the replacement of the component is required.

    However, the most common failure is damage to the coil due to impacts from stones and elements found on the track. These can cause deformations and perforations in the pipes. If the damage is significant, complete component replacement may be required, but if it is minor, the damaged area can be repaired. Although not all workshops agree to carry out this type of work because it can be complex and meticulous operations, there are some centers specialized in these repairs.

    To repair the radiator in this case, before sealing the possible cracks by means of aluminum welding, it is convenient to sand the area to be treated with P80 type sandpaper to eliminate the layer of aluminum oxide and thus promote adhesion. Depending on the degree of failure, the leak can be quickly repaired using steel-filled epoxy putty.

    In the event that the crack is of considerable size and cannot be repaired using a structural adhesive, the material must be provided by means of an aluminum weld. Currently, the Radiators are made of this material which, thanks to its lightness, has replaced brass and copper even though these are better conductors. It is essential that the weld bead is applied continuously to ensure a robust joint and avoid deformations and it is advisable to mask the contiguous areas to protect them from welding projections that can deform the pipes.

  • Application curing. In the event that the leak can be repaired with a product such as epoxy adhesive, the time stipulated by the manufacturer, never less than one hour, of the product must be respected to ensure optimal curing of the area.
  • Clean the area. Once the coating product has cured or after an aluminum electrode welding, the surface should be slightly smoothed to avoid protrusions, remove the slag and clean the area properly with a degreasing product such as LOCTITE SF 7840.
  • Refill the coolant circuit. If, in addition to repairing the car’s radiator, it has been decided to replace the coolant (highly recommended action), it is essential to choose the right product according to the technical data sheet and the manufacturer’s recommendation. Otherwise, the correct operation of the cooling system could be affected.
  • To fill the circuit, it is important to know its capacity and the type of refrigerant (this information can be found in the vehicle’s user manual). Commonly, the manufacturer’s recommended mixing ratio is 60% coolant and 40% water. The tank must be topped up to the recommended level (marked on the tank itself) for optimum engine performance.
  • At this time, it is advisable to start the engine and wait for the liquid to flow through the circuit. The level of liquid in the reservoir is going to decrease, so it must be topped up until it reaches the recommended level again.
  • Bleed the circuit. Through the valve located in the upper part of the radiator, the circuit must be bled. It is recommended to leave the valve open for about 10 minutes, with the engine running, to allow excess air to escape.
  • Carry out a road test. Once the repair is finished, it is essential to run in to verify that the temperature reached by the vehicle is adequate and remains stable (normally around 90 ºC) and that the car’s heating is working properly.
  • Once the test is finished, it is advisable to check the coolant level again and, if necessary, top it up to the optimum level.

    Conclusion

    Checking the coolant level and its degree of aging and wear is a common action in all preventive maintenance. This task is essential since, in some cases, it may show the need to repair the car’s radiator. Also, failure to ensure correct fluid quality and level can lead to higher grade breakdowns. Choosing the best radiator flushes is essential as not all products are effective so a thorough review and other customers’ feedback are of great help.

    About the author

    Andrew Clark