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Best Radiator Stop Leak – Stop Coolant Leaks with These Top Products

Discovering problems with a crucial component in your vehicle is unpleasant, to say the least. If you suspect your radiator might be leaking, we’re here to help.

Replacing your radiator doesn’t come cheap. But you may have heard about products that can potentially fix the issue for you without having to replace the whole radiator expensively? The best radiator stop leak products might be able to do just that.

Radiator stop leak being poured into the cooling system through a funnel

In this article, we’re going to discuss how these products work and what sort of trouble they can—and can’t—fix. We’ll then detail what you should consider before buying one for your car.

Lastly, we’ve rounded up and recommend some of the best radiator stop leak powders, liquids, and tablets on the market. We hope it will help you find one that’s right for you and your vehicle.

Quick Links to Our Top Recommendations for Best Radiator Stop Leak

Note: Clicking the above links will take you to further information, current prices and customer reviews on Amazon.

What is a Radiator Stop Leak?

If you’ve never used one before, the name can be a little misleading. These substances can plug up leaks in your radiator, but not exclusively inside your radiator.

They circulate throughout your automobile’s cooling system. In the process, they target cracks or holes that result in lost coolant (antifreeze).

We’ll be delving into the science behind how they work in the next section. First, let’s cover how your vehicle’s cooling system functions.

This will help you better understand how these leak-fighting substances operate. For readers who are experts on your car’s internal workings, feel free to skip ahead.

How Your Cooling System Works

The environment inside your engine runs hot. An estimated 70 percent of energy from the combustion of fuel ends up as heat. Without a cooling system to counteract this, your engine would overheat.

Automotive radiators are not like the ones we use at home during the winter to stay warm. They dissipate heat rather than retain it.

They contain coolant liquid that circulates through pipes and tubes in and around your engine. The liquid is typically a mixture of water and antifreeze.

The exact quantities of each will depend on the vehicle make, model, and owner. The maximum antifreeze-to-water ratio is 70 percent antifreeze to 30 percent water.

As the coolant flows, it collects heat produced by your engine’s internal mechanisms. The now-hot fluid is then returned to the radiator.

If the solution isn’t hot enough, the thermostat blocks it from entering. Only once the liquid is at a certain temperature will it be allowed in.

Radiators can be made of aluminum, other metals like copper, or both. Newer models can include plastic fittings.

The core of the radiator consists of many slim tubes built with fins. This design is to promote heat transfer. The fan draws in air entering through your car’s grille for

additional cooling.

A pressure cap increases the coolant’s boiling point. It also regulates pressure. Otherwise, tubes and hoses would burst.

If the liquid exceeds a certain pressure, it’s carried to the overflow tank. Once cooled, the fluid is put back into action.

The pump moves the solution through your engine in a continuous loop. Altogether, this innovative system is what keeps your engine from overheating.

The Danger of Leaks – And How to Identify Them

If the coolant is escaping, the integrity of the whole system will be compromised. In turn, this can lead to an overheated engine, as well as other issues.

Existing holes can grow larger with time if neglected. Antifreeze can damage other components if it spreads where it shouldn’t.

There are a few signs that indicate you might have a leak on your hands. You may notice your engine is prone to overheating more often.

Another symptom is that your vehicle is suddenly thirstier for coolant. If you have to top up your coolant frequently, you likely have leaks.

You may also see antifreeze puddles underneath your car. Remember, antifreeze is brightly colored (neon green, pink, or orange). It also has a sweet odor.

A sweet smell emanating from underneath your hood shouldn’t be dismissed. Antifreeze is highly toxic to humans, companion animals, and wildlife.

Other potential symptoms include visible wear and tear. For instance, bulging or cracked rubber hoses, or corrosion on metal surfaces.

Good maintenance practices will lower the risk of most of these scenarios. Just like motor oil, the chemical composition of coolant fluid changes as it ages.

You have to flush this liquid and replace it every so often. If the color has dulled or you see rust particles floating around, it’s too old. Flushing also cleans out debris that can build up inside your radiator and clog it.

How do Radiator Stop Leak Products Work?

The chemicals circulate throughout your car’s coolant system. The ingredients of these products vary, depending on the manufacturer.

Most brands are secretive about the specific formula. You’re not likely to see a list of each and every chemical on the bottle or package.

In general, compounds are selected for their ability to bond with metals and plastics. This allows the substance to seal up cracks, tears, and holes.

Sodium silicate is one such material—it’s also known as liquid glass. It is capable of sealing breaches in metals, as well as ceramics and concrete. Other manufacturers take advantage of nanotechnology. Materials (e.g. chemicals) are altered on a very small scale.

Stop-leaks can include other beneficial agents or additives. These may moisturize brittle rubber, or add to the properties of your coolant, such as enhanced heat transfer.

Other additives can prevent corrosion and the buildup of scale. You’ll also find products that claim to control electrolysis.

This is a term often used to describe galvanic corrosion. When different metals come in contact with each other, it can result in deterioration (e.g. pitting, rust). This can occur in coolant systems, as there are dissimilar metals within it.

How Effective are They? Can They Repair any Radiator Leaks?

Unfortunately, these products aren’t miracle solutions. With a radiator that is severely damaged, a radiator stop leaks won’t help. You can’t expect to patch up a rusted out radiator that has large cracks or holes.

A rubber hose with a sizable rip in it won’t be miraculously repaired. The same goes for a cracked coolant overflow tank.

These chemicals do best on small breaches. You’re most likely to see success plugging up hairline cracks and tiny pinholes.

On the same note, the location will influence how effective a product is. Let’s say you have a hole at the top of your radiator: Most likely that area doesn’t see much fluid. To have a chance at success, the sealing compound has to circulate.

Taking a look under the hood should clarify things for you. If you’re not confident in your automotive knowledge, you may want to check with your mechanic. Doing nothing and leaving it to worsen will only cost you more money in the long term.

Buying Guide — Choosing the Correct Radiator Stop Leak

Before you get your credit card out, take a look through our buyer’s guide. You want to be sure you purchase the right product for you and your vehicle.

Different Types of Leaks

We touched on this in the section above. Where is your leak located? How bad is it? A hairline crack, or something worse?

Worn out hoses will have to be changed, one of these substances won’t help. A corroded radiator is probably beyond saving. So are metal pipes and tubes throughout your engine with large breaches.

Temporary Vs. Permanent Stop Leaks

If you’re looking to postpone a trip to your mechanic, a temporary stop-leak might work for you. If you want something more durable, look for a permanent solution variety. These are made to form resilient bonds that won’t wear away easily.

Type: Liquid, Powder, Or Tablet

You can choose between one of these compounds. Each has a set of advantages and disadvantages.

Powders and tablets are easier to transport as they’re compact. If you’re buying a temporary stop-leak, you’ll want to keep it on hand for repeat treatments. In these forms, they won’t take up much space in your car.

In the event of a spill, liquids and powders are harder to clean. If you’re worried about this, tablets might be a good option for you. If you drop one where you shouldn’t, it won’t make a big mess.

However, radiator stop leak tablets usually require gloves to handle. Powders and liquids come in containers so that you don’t have to touch the chemicals directly.

Be wary of causing blockages, particularly if your system hasn’t been flushed for a while. A thick, gel-like liquid may gunk up your pipes. Dumping in large amounts of

powder could also cause a clog.

Price-wise, tablets and powders tend to be cheaper. Liquids can be more expensive, but you usually get multiple treatments in one bottle.

Is it Compatible With Your Vehicle and Your Antifreeze?

Using the wrong product can have grave consequences. When you’re dealing with chemicals and your vehicle, it’s better to be safe rather than sorry.

You need to make sure the one you’re considering is compatible with your car and the antifreeze it currently contains. You don’t want to end up at your mechanic to have your whole coolant system professionally cleaned out.

Time to Fix Leak

How long will it take for the leak to be fixed? Ideally, it should work as quickly as possible. Take note that some brands will require you to drive your car around. With others, you can leave the engine idling instead.

Long treatment times aren’t convenient for everyone. Some of you might not be interested in driving your car around for half an hour or longer.

Does the Coolant System Need Flushing?

Flushing out the entire system might sound daunting to some of you. If you’re unable or unwilling to do this, check product guidelines carefully. You’ll want to buy one that can be added to your antifreeze directly.

Best Radiator Stop Leak – a Detailed Look at Our Top Recommendations

We’ve listed our top recommendations for you to choose from below, where we’ve detailed everything you need to know to make an informed decision.

Bar’s Leaks Liquid Aluminum Stop Leak

Bar's Leaks 1186 Liquid Aluminum Stop Leak - 16.9 oz

Liquid aluminum will appeal to inexperienced vehicle owners. This liquid can treat any vehicle, regardless of coolant type. It’s compatible with all types of antifreeze, including extended life variations.

You don’t need to concern yourself with flushing or draining your system. All you have to do is add it directly to your radiator. If that isn’t accessible, you can treat your reservoir with it instead.

A single bottle of Bar’s Leaks will be enough for the majority of coolant systems. If you have a four-cylinder engine, start with half a bottle. You won’t have to wait long to determine if this product worked or not. It takes a maximum of 20 minutes to be effective.

If symptoms persist, you can attempt a second treatment. You don’t necessarily have to take your car out for a drive. The guidelines state that keeping the engine idling is acceptable too.

The formula includes a cooling additive for enhanced coolant performance. It lowers the surface tension of your cooling fluid to boost heat transfer. This should discourage overheating, which is always a plus.

Features and Specifications

  • Bottle capacity: 16.9 ounces.
  • Liquid type.
  • Available as a single bottle or a pack of six.
  • Compatible with all types of antifreeze.
  • Suitable for all water-cooled vehicles.
  • Standard coolant system treatment: one bottle.
  • Results in 10 to 20 minutes.
  • No flushing or draining required.

What We Like

  • Simple to use.
  • Suitable for all vehicles and antifreeze types.
  • Reduces water temperature.
  • Successful at stopping up most minor breaches.
  • Users report long-lasting results.
  • Can be used even if bottle freezes.
  • Fast results.

What We Don’t Like

  • Some users experienced clogs.
  • Might not work on larger breaches.


This liquid should solve minor hairline and pinhole leaks rapidly and it’s easy to use. In the event that you let the bottle freeze, the liquid is still viable once thawed.

If you’re curious to learn more about Bar’s Leaks liquid aluminum, click the link below.


Click to Learn More / Buy from Amazon


K-Seal Multi-Purpose One Stop Permanent Coolant Leak Repair

K-SEAL Coolant Leak Repair, ST5501 8oz, Multi-Purpose Formula Stops Leaks in the Radiator, Head Gasket, Block, Water Pump Casing, Heater Core, and Freeze Plug - Pour and Go - Trade Trusted-Stop Leak

This product from K-Seal is a comprehensive treatment for perforations throughout your engine. It’s also rated to work as a head gasket sealer, blocks, and seals.

Despite all these capabilities, treatment is straightforward. K-Seal leak repair can be mixed with any antifreeze and poured directly into your radiator. For standard treatment, your main responsibility will be shaking the bottle for half a minute.

Afterward, all you have to do is idle your engine for 20 to 30 minutes. Particles in the formula mesh together over the leaks. The seal is then cured through exposure to heat and gases inside your engine.

If the mention of particles has you concerned about clogs, don’t be. They aren’t large enough to block tubes or pipes. For head gasket repair, the instruction manual details treatment steps for over-pressurized systems. This is practical for individuals who aren’t fluent in mechanics.

The guidelines also specify the maximum size of holes and cracks this liquid works on. If the treatment is successful, you’ll know that holes or cracks don’t exceed the stated measurements.

Features and Specifications

  • Bottle capacity: 8 ounces.
  • Liquid type.
  • Permanent repair.
  • Works for head gasket and radiator repair and block/head sealing.
  • Standard cooling system treatment: one bottle.
  • Compatible with all types of antifreeze.
  • Repairs holes up to 0.635 millimeters; cracks up to 11 millimeters long by 0.025 millimeters wide.
  • Results in 20 to 30 minutes.
  • No draining or flushing required.

What We Like

  • Versatile applications.
  • Simple to use.
  • Helpful instructions.
  • Short treatment time.
  • Forms a resilient seal.
  • Small bottle—a little goes a long way.

What We Don’t Like

  • Must be shaken thoroughly to avoid clogs.
  • Might not work on bigger fissures.


If you want an all-in-one multipurpose treatment for leaks in your engine, K-Seal’s Pour and Go might be for you. The clear directions make it appropriate for users of any level.

If you’re interested in buying a bottle, follow this link.


Click to Learn More / Buy from Amazon


Bar’s Leaks Cooling System Repair

Bar's Leaks Cooling System Repair - 16.9 oz

This temporary radiator stop-leak is great if you want to buy yourself some time. You can plug up holes and cracks while you save up for your mechanic’s bill. Although this product won’t last forever, it can still be useful. Some users have reported stopping larger leaks that were causing excessive coolant loss.

Another benefit is it could reduce overheating. As with the other Bar’s Leaks liquid we have reviewed, the formula includes cooling additives. This will enhance heat transfer in your cooling system, combating overheating.

If your cooling system is less than 1.5 gallons, half a bottle is sufficient. For standard systems, one bottle should do the trick. Larger systems will require one bottle for every 4 gallons.

You won’t have to flush or drain your coolant system unless it’s dirty. It can be mixed with any brand of antifreeze directly.

An advantage of this cooling system repair is that it’s freeze-resistant. If you happen to leave a bottle in the cold, you can thaw it out and still use it. This is handy when you buy a pack of four instead of a single bottle.

Features and Specifications

  • Bottle capacity: 16.9 ounces.
  • Temporary reapair.
  • Liquid type.
  • Available as a single bottle or a pack of four.
  • Compatible with all types of antifreeze.
  • Standard cooling system treatment: one bottle.
  • Results in 15 to 20 minutes.
  • No draining or flushing required (unless system is dirty).

What We Like

  • Users have reported success plugging larger leaks temporarily.
  • Effective on pinhole and hairline breaches.
  • Short cure time.
  • Contains additives to enhance heat transfer.
  • Freezing won’t sour the product.

What We Don’t Like

  • May require repeated treatments.
  • Can clog dirty systems.


If you want a short-term radiator stop leak solution for big breaches, this product is an ideal choice. For minor leaks, you can expect it to last for a long time.

Are you eager to try Bar’s Leaks cooling system repair on your car? Follow the link below.


Click to Learn More / Buy from Amazon


Bar’s Leaks Hdc Radiator Stop Leak Tablet

Bar's Leaks HDC Radiator Stop Leak Tablet - 60 Grams

These tablets are capable of sealing small leaks in your coolant system. If you have tiny perforations that don’t warrant new parts, these tablets may be right for you. The tablets work by dissolving in your coolant, from where the particles gather at the hole or crack and build up inwards.

Unless you have a dirty coolant system, clogs are unlikely to happen. There’s no need to stress about accidentally damaging other components. The HDC tablets are harmless to all metals, hoses, and plastics.

Once you idle your engine for 15 to 20 minutes, the heat will allow the patch to solidify. The formula is designed to seal pores in aluminum and cast iron. Additionally, it has corrosion-inhibiting properties.

The tablets can also control electrolysis. This phenomenon can do serious harm to your coolant system if it occurs.

Your water pump seal will also appreciate a dose of HDC radiator stop leak. The tablets contain conditioning agents for lubrication. A moisturized rubber seal (of any sort) is more effective than a brittle, dried out one.

To treat, just drop whole tablets in your radiator or coolant reservoir. Alternatively, you can dissolve the tablets into warm water first.

Features and Specifications

  • One package includes six tablets.
  • Also available as a pack of 12.
  • Six tablets treat up to 3 gallons of coolant.
  • Compatible with all types of antifreeze.
  • Results in 15 to 20 minutes.
  • No flushing or draining required (unless system is dirty).
  • Harmless to all coolant system materials (plastics, metals, aluminum, etc).
  • Lubricates water pump seal.
  • Inhibits corrosion and electrolysis.

What We Like

  • Contains lubricating additives.
  • Fast results.
  • Effortless treatment.
  • Efficient at sealing tiny leaks.
  • Safe for use on all metals, hoses, plastics, etc.
  • Can hinder internal corrosion.

What We Don’t Like

  • Can clog dirty systems.
  • Doesn’t last long for bigger leaks.
  • Shouldn’t be handled by bare skin.


You can rest assured these tablets won’t harm any of the materials in your coolant system. Aside from stopping leaks, they’ll also condition your water pump seal and fight corrosion.

Are you thinking about purchasing a package for your vehicle? Click this link to get one.


Click to Learn More / Buy from Amazon


Genuine Gm Cooling System Seal Tablet

Genuine GM (12378255) Fluid 3634621 Cooling System Seal Tablet - 4 Grams, (Pack of 5)

These organic tablets will appeal to General Motors vehicle owners. They’re produced by ACDelco, which makes a range of GM-specific products and equipment.

The owner manuals on certain General Motors vehicles recommend using these tablets.

If you want to take preventative measures against leaks, consider this product. They target porosity in metals and will stop up microscopic cracks before they escalate. The tablets are formulated to be safe for your coolant system. You can rest assured they won’t wear out plastic, metal, or aluminum.

They also have a range of protective capabilities. The first one is neutralizing pH: high acidity or alkalinity isn’t good for any of the parts in your engine. Secondly, corrosion and the formation of scale are inhibited. Finally, electrolysis is controlled.

Treating your coolant system is a breeze. You can either crush the tablets or drop them in. It’s recommended to flush and drain coolant systems that haven’t been cleaned in a while.

Features and Specifications

  • One package contains five 4-gram tablets.
  • Organic formula.
  • Compatible with all types of antifreeze.
  • Harmless to all coolant system materials (plastics, metals, aluminum, etc).
  • Five tablets will treat up to 32-quart radiator capacity.
  • Lubricates internal components.
  • Inhibits corrosion and scale formation.
  • Controls electrolysis.
  • No flushing or draining required (unless system is dirty).

What We Like

  • Won’t cause wear and tear on internal components.
  • Protective abilities.
  • Less toxic than other alternatives.
  • Especially for General Motors engines.
  • Reputable manufacturer.

What We Don’t Like

  • Only works for minor leaks.
  • May discolor antifreeze.
  • Can clog dirty systems.


If you own a General Motors vehicle and want to stop minor breaches from escalating, these tablets may be the ideal solution for you. They’ll also appeal to users who prefer to use organic concoctions.

In case you’ve decided on these ACDelco coolant system tablets, you can purchase them here.


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J-B Weld Perm-O-Seal Radiator Stop Leak

J-B Weld DS-114 PERM-O-Seal Radiator Stop Leak - 0.7 oz.

This concentrated powder by J-B Weld comes in a 20-gram tube. This product is intended to seal holes and cracks in the long term. The powder is rated to fix mild to severe coolant loss.

If you suspect you have smaller fissures, the treatment process is simple. You pour the contents of the whole tube into your radiator while your car engine is running.

There are separate instructions for big breaches. You’ll have to position a bucket (or container of your choice) underneath the spot coolant escapes from. Then, pour the solution back into the radiator.

This is to give the J-B Weld Perm-O-seal the opportunity to take effect. You also get the reassurance that you’re not wasting powder. Treatment time will vary, depending on the vehicle. You’ll know the problem is solved once the leak stops.

The fine powder is made to circulate rapidly throughout your radiator and coolant system. The particles aren’t large enough to cause clogs.

It’s also formulated not to harm any of your car’s internal works. Perm-O-seal is non-toxic and won’t damage plastics or metals. Plus, your vehicle will benefit from rust-inhibiting and lubricating ingredients.

Features and Specifications

  • One tube of powder, 20 grams.
  • Non-toxic.
  • Also available as a package of two tubes.
  • One tube per vehicle treatment.
  • Harmless to all coolant system materials.
  • Contains lubricants and rust-inhibitors.

What We Like

  • Long-lasting seal.
  • Acts as a lubricant.
  • Fights corrosion.
  • Won’t harm your coolant system.
  • Fine particles to avoid clogs.
  • Specific instructions for treating larger perforations.
  • Concentrated formula.

What We Don’t Like

  • Must be poured into radiator while the engine is running.


This long-lasting powder is rated to work on breaches great and small. If your vehicle is gushing coolant, J-B Weld Perm-O-seal might be suitable for you.

To buy a tube for yourself, check it out at this link.


Click to Learn More / Buy from Amazon


Prestone Radiator Sealer Stop Leak

Prestone AS145 Radiator Sealer Stop Leak - 11 oz.

This sealer by Prestone contains a combination of synthetic and natural ingredients. The liquid is capable of plugging up holes of up to 0.02 by 0.5 inches. It can bond to plastics as well as metals, meaning it could benefit your water pump seal too.

It’s always good to have a measurement rating. If the substance is ineffective, you’ll know the perforation you have exceeds a certain size.

This product will appeal to users looking for a durable seal. Prestone uses fibrous particles made from the same materials found in bulletproof vests. In spite of this, it shouldn’t result in blockages—even in tight spaces like your heater core.

The formula is also packed with corrosion-fighting additives. Aside from plugging up holes, it can protect metals from pitting and rust. This means it can serve as a preventative as well as a cure.

Features and Specifications

  • Bottle capacity: 11 ounces.
  • Available as a single bottle or a pack of six.
  • Liquid type.
  • Systems larger than 12 quarts require two bottles.
  • Seals breaches up to 0.02 by 0.5 inches.
  • Includes rust inhibitors.
  • Doesn’t require flushing or draining (unless system is dirty).
  • Recommended to use Prestone antifreeze after treatment.

What We Like

  • States the maximum size of cracks it can seal.
  • No need to flush or drain clean systems.
  • One bottle is enough for most vehicles.
  • Unique formula.
  • Protects against corrosion and pitting.

What We Don’t Like

  • A few users reported only short-term results.


With rust-hindering properties, this liquid has protective as well as sealing qualities. It’s also interesting to know that it contains the same fibers as found in bulletproof vests.

For readers who want to learn more about this product, you can find it here.


Click to Learn More / Buy from Amazon


Bar’s Leaks Block Seal Liquid Copper Intake and Radiator Stop Leak

Bar's Leaks 1109 Block Seal Liquid Copper Intake and Radiator Stop Leak - 18 oz.

Those of you with high-mileage or aging vehicles will appreciate this liquid. As our automobiles collect miles, leaks can become a facet of daily life. Metals grow more porous and rubber seals start to dry out.

Bar’s Leaks liquid copper block seal is effective on all the vulnerable components in your engine. It can repair breached radiators, blocks, head gaskets, and freeze plugs.

The liquid contains multiple ingredients that act in steps to seal cracks and holes. First, a wetting agent prepares the edges of the perforation by cleaning it.

Next, fibers catch onto the sides of the hole, gradually bonding together. Ingredients include copper, an ionic mineral, and other organic and synthetic fibers. One of the latter is sodium silicate, a multipurpose bonding compound.

All of these materials form a secure plug. As you run your engine, heat stabilizes the seal to cement into liquid glass. The higher the temperature, the stronger this patch will become.

This technology allows the liquid copper block seal to target moderate to severe fissures. As this liquid is intended to be permanent, you can expect long-lasting results.

Features and Specifications

  • Bottle capacity: 18 ounces.
  • Available as a single bottle or a pack of six.
  • Liquid type.
  • Permanent repair.
  • Repairs leaks in radiators, head gaskets, blocks, and freeze plugs.
  • Standard cooling system treatment: one bottle.
  • Compatible with all types of antifreeze.
  • Results within 20 to 30 minutes.
  • No flushing or draining required.

What We Like

  • Powerful sealing action.
  • Easy to treat any vehicle.
  • Works on more than just your radiator.
  • Good for high mileage and older vehicles.
  • Highly effective on minor breaches.

What We Don’t Like

  • In water-only systems, two bottles are needed for treatment.
  • May not be suitable for all vehicles, due to sodium silicate content.


If your car has a well-worn engine, this product is ideal for targeting breaches of all types. You can also benefit from a seal that will plug up leaks long-term.

Check the link below to buy Bar’s Leaks liquid copper block seal for your car.


Click to Learn More / Buy from Amazon


Dike Temporary Radiator Stop Leak

Dike Temporary Radiator Stop Leak

This fast-acting liquid is great to keep in your vehicle for emergencies. It can be mixed with any type of antifreeze, and you won’t have to drain or flush your system.

Dike works swiftly in just 15 minutes, you won’t smell or see escaping coolant. Smaller holes could be sealed in less time, seconds instead of minutes.

You’ll be able to safely drive your car to a mechanic to sort out the problem. The short cure time will prevent further loss of antifreeze.

Although it’s branded as temporary, some users report long-lasting sealing action. You might be able to buy more time than you’d expect before professional intervention is needed.

There’s little risk of clogs with Dike temporary radiator stop leak. It can safely flow through even the smallest passages without resulting in blockages.

For people who like to take precautions with their cars, Dike can be used as a preventative. It conditions head gasket seals and can target hairline cracks before they escalate.

Features and Specifications

  • Bottle capacity: 16 ounces.
  • Liquid type.
  • Temporary repair.
  • Compatible with all types of antifreeze.
  • One bottle per 4 gallons of coolant.
  • Results within 15 minutes.
  • Conditions head gasket seals.
  • No draining or flushing required.

What We Like

  • Includes seal-conditioning additives.
  • Won’t clog heater core.
  • Fast-acting results.
  • Lasts a long time.
  • Also functions as a preventative.

What We Don’t Like

  • In filtered systems, filter must be removed prior to treatment.


This stop-leak is appropriate for almost any vehicle owner to keep in the trunk. Whether you want to prevent coolant loss or be prepared for it, Dike temporary radiator stop leak is a good choice.

Buy yourself a bottle at the link below.


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Alumaseal Radiator Stop Leak Powder Blister Card

AlumAseal ASBPI12 Radiator Stop Leak Powder Blister Card - 20 g

This easy-to-use powder plugs leaks without doing harm. The powder is too fine to provoke blockages and won’t harm plastics or metal.

The formula is enriched with conditioning additives to moisturize seals and inhibit rust formation. For minor coolant loss, you can keep using this powder as a preventative.

Since the powder is conveniently packaged, you can store it anywhere in your car. You won’t have to be concerned about getting home when noticing a spill. In the event that you’re caught out on the road with a sudden leak, you’ll be protected.

AlumAseal can target perforations of all sizes throughout your radiator. As it lubricates seals, it can work on other leaks too (e.g. in your head gasket).

Features and Specifications

  • One package contains 20 grams of powder.
  • Available as a pack of 12.
  • Compatible with all types of antifreeze.
  • One packet treats standard-size coolant systems.
  • Harmless on all internal system components.
  • Inhibits rust and lubricates seals.

What We Like

  • Effective on moderate to severe breaches.
  • Lubricates seals.
  • Won’t cause blockages.
  • Contains corrosion inhibitors.
  • Users have experienced long-lasting results.

What We Don’t Like

  • Can clog dirty systems.
  • Can take up to 300 miles to seal leaks.


Treating your vehicle with this powder couldn’t be easier. Keep a packet on hand for emergencies or treat your leaky radiator with it today.

Check out AlumASeal at this link.


Click to Learn More / Buy from Amazon



As you can see, there is a diverse variety of radiator stop leak products on the market. Even if your car is well-maintained, it’s practical to have one of these substances on hand.

Leaks can start without warning. You want to keep coolant loss to a minimum until you can get the issue solved permanently. This product can allow you to get your vehicle to a mechanic for a better look over and more permanent repair.

We hope you’ve found in our guide the best radiator stop leak for your vehicle’s needs. If you have any questions or comments, we’d love to hear your thoughts. We’ll respond to every comment!


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From childhood go karting and motocross, to collecting and obsessing over scalextric, matchbox and radio controlled cars, I've always had an obsession with cars. Learning through manuals, books, trial and error, and more knowledgeable family members, I've also enjoyed tinkering with the mechanics and electronics of any vehicles I've owned. Now, over 3 decades later, I've started this site as a place for me to share my knowledge, to teach others how to care for and maintain their vehicles themselves, at home, so they can get the most of their vehicles and save a pretty penny compared to always seeking out professional help.

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