Best Radiator Stop Leak 2020 – Quick Solution For A Moderate Radiator Leak

Whether you own a compact car or a heavy-duty pickup truck, your radiator is one of your ride’s most crucial components. It’s responsible for absorbing and removing heat from the engine block. Without it, your engine would constantly overheat. Your vehicle’s performance would suffer and it would pose a significant safety risk.

Despite the careful engineering and strong construction methods used to manufacture modern radiators, they are not immune to damage. Radiators are comprised of a series of tubes and hoses. They’re filled with coolant, which carries heat away. These tubes and hoses are subjected to significant wear and tear. Leaks are quite common. You can easily diagnose the problem by taking a look under your car. If you see a puddle of sweet-smelling fluid that looks like water, you may be dealing with a leaking radiator. So what are you supposed to do?

Ideally, you would bring your vehicle to an automotive professional for repair. Unfortunately, that’s not always feasible due to location and cost. Radiator stop leaks can provide you with the solution you need. These products offer a quick and effective solution to moderate radiator leaks. They’re very easy to use and can drastically improve your engine’s performance. Here’s a list of some radiator stop leak products you should try.


Bar’s Leaks Grey Radiator Stop Leak

This options from Bar’s is designed to stop moderate radiator leaks. It’s formulated to work on a wide variety of radiator designs and materials. It’s also compatible with all types and colors of coolant, so you don’t have to worry about any unwanted effects. The product comes in liquid form. One bottle holds approximately 6 ounces, which is more than enough to treat a radiator that holds up to 3 gallons of coolant.Pros:

  • Works with all types of coolant
  • Formulates for quick results
  • Is capable of stopping moderate leaks
  • Convenient 6-ounce bottle



Bar’s Leaks Liquid Copper Block Seal Radiator Stop Leak

Another great product from Bar’s, this option is versatile enough to repair a wide range of issues. In addition to stopping leaks in your radiator, it can be used to fix blown gasket heads, heater core problems, freeze plug leaks, and much more. The liquid formula is compatible with most coolants. Not only that, but it can also tackle larger leaks. The product is very simple to use. There’s no need to drain your radiator system. Simply pour the 18-ounce bottle into the radiator, run the engine, and you’re done.Pros:

  • Fixes mutlipe issues
  • Can take care of large leaks
  • Contains 18 ounces of fluid
  • Doesn’t require you to drain radiator



Prestone Radiator Stop Leak with Kevlar

This innovative radiator stop leak product takes advantage of the power of kevlar. It’s formulated to seek out leaks within your radiator system and seal them without causing corrosion or clogging. It’s suitable for all types of cooling systems for your peace of mind. It contains both liquid and tablets. The two-step process requires you to add the tablets into your radiator first. This is then followed by the metallic slurry. After running your engine for a while, the product will flow through your radiator and take care of leaks.Pros:

  • Utilizes durable kevlar
  • Two-step system with tablets and liquid
  • Contains 16.5 ounces of fluid
  • Suitable for all cooling systems



Speedol F6 Radiator Stop Leak Cooling System Sealer

The Speedol radiator stop leak sealer can take care of small leaks in as little as five minutes. The liquid sealer can be poured directly into a clean and cool radiator system. It’s compatible with all types of refrigerants and will not cause any corrosion. In addition to sealing leaks, the product can also prevent unwanted seepage at the head gaskets.Pros:

  • Easy to use
  • Works in as little as 5 minutes
  • Contains 10.14 ounces of fluid
  • Suitable for all cooling systems


  • May require cleaning
  • Only repairs minor leaks
  • May not fully circulate radiator if there’s too much air pressure



Perm-O-Seal Radiator Stop Leak

If you’re looking for a product that can provide you with permanent results, consider this option from Perm-O-Seal. It’s a powder formula that contains metallic particles. It also has a rust inhibitor and water-based lubricants for better performance. The powder can be used in a myriad of different radiator system. It’s designed to be effective without clogging your system or affecting performance.Pros:

  • Easy to use
  • Includes rust inhibitor
  • Contains 0.7 ounces of powder
  • Designed to provide permanent seal on minor leaks


  • May require cleaning
  • May be messy to use



Alumaseal Radiator Sealer

The Alumaseal radiator stop leak powder can provide you with quick results. It’s a powder sealer that’s compatible with all coolants. This ensures that you don’t have to worry about unnecessary reactions or damage. You can also use the product with metal, plastic, and rubber systems. This product can treat large radiator systems that hold up to 5 gallons of coolant.Pros:

  • Compatible with all types of coolant
  • Works with plastic, metal, and rubber components
  • Can treat 5 gallon systems
  • Designed to work quickly


  • May be messy to use without funnel



Radiator Stop Leak Buying Guide

Choosing the right radiator stop leak for your vehicle and situation is important. Radiators are not cheap to replace. You want to make sure that the product you choose doesn’t do any further damage to your vehicle. There are plenty of options to choose from. Before you purchase the first thing you see, there are some considerations you need to keep in mind.

Radiator Compatibility

First and foremost, it’s crucial to make sure that a particular product is compatible with your radiator. To the average car owner, all radiators are the same. Truth is, radiator designs can be just as complex as the engine itself. There are many different types of radiators out there. Some are made out of plastic and aluminum while others utilize tough materials like copper or brass.

Radiators can also differ in functionality. For example, some cars have a cross flow radiator while others utilize a down flow radiator. It’s a good idea to check in your vehicle manufacturer’s handbook to see what type of radiator your car has. While many radiator stop leak products are designed to work with a range of radiator designs, you may find that a particular product is more suited for a specific design or material. The main issue you’re looking to avoid is clogging. If you use a product that’s not suitable for your radiator, the product can prevent coolant from flowing freely. Examine the product’s directions thoroughly before you use it to make sure its compatible.

Chemical Formula

Products that help to stop leaks are made up of chemical compounds. Typically, the formulas are designed to react with oxygen. When this happens, the chemicals bind with the material of your radiator. As with any chemical additive, it’s important that you scrutinize the chemicals and make sure that they’re safe to use in your vehicle. While it is rare, there is a possibility that some stop leak products will interact unfavorably with your coolant or engine build.

Some may not work if there is any dirt or debris in the system. If that’s the case, you would need to clean out the radiator with a flush. There are even products that require you to empty out the coolant altogether.

Types of Radiator Stop Leak Products

Once you have figured out which radiator stop leaks are right for your vehicle’s radiator, you can start to look into the different types of products available. Radiator stop leaks are available in three different forms. They all do the same job effectively. However, the type of product you get can affect ease of use, convenience, and portability.

Tablets are a great option if you want something that you can keep in your vehicle at all times. The small tablets hold their shape and take up very little space. They can be dissolved in warm water or dropped into the coolant directly. Once the tablet has been fully dissolved, the ingredients can start to flow through the radiator and plug up any leaks.

Stop leak fluids are the most common product you’ll find. They come in small plastic bottles that are designed for easy pouring. You can also find larger bottles if you want to buy in bulk. To repair a leak, all you have to do is pour the liquid into the radiator.

Radiator stop leak powders contain all the necessary ingredients and particles to address issues quickly. To use this form, you have to empty the contents of the package into your radiator. While they are convenient and don’t take up much storage space, they can be more difficult to use if you don’t have a steady hand. It’s a good idea to invest in a small funnel to avoid messes. You may also want to get a particle mask to prevent accidental inhalation.



Frequently Asked Questions

Q: How do radiator stop leaks work?

A: The idea behind radiator stop leak products is very simple. The unique formula contains particles and chemical compounds. When it travels through the radiator system, it bonds with the material to plug up any holes. It’s as if you were patching a hole with duct tape. However, the repair is being done inside the radiator for maximum efficiency. When the leak is mended, the coolant is able to flow freely and do its job to keep the engine cool.

Q: How can I confirm a radiator leak?

There are a number of ways you can diagnose the problem on your own. Oftentimes, the first sign of a leak is an overheating engine. Keep a close eye on the engine temperature gauge. If it appears to get hotter, this could mean that the coolant is not doing its job.

When you park the car, take a look under the body. Leaks occur directly underneath the engine. Coolant usually looks like water. However, it has a sweet smell and produces a rainbow color spectrum, similar to that of oil, when it’s under direct sunlight.

Finally, you can check the coolant levels. Let your car cool down completely before you do this, as heat from the radiator could cause burns. Once your vehicle is cool, simply open the radiator cap and see how much coolant there is. If it’s lower than normal, you probably lost some during a leak.

Q: Where do you add the radiator stop leak product?

Check the instructions of your stop leak product for exact details. Not every product is the same, so it’s important that you read through the instructions to ensure that you’re doing every step correctly. Radiator stop leak products are introduced into the system through the radiator cap. This small cap near the engine block twists off to provide easy access.

Q: Do radiator stop leak products require any preparation?

This depends on the condition of your radiator. It’s always recommended that you use radiator stop leak products on a clean radiator system. Unfortunately, leaks expose your system to dirt and debris. Introducing a chemical additive into a dirty system could cause further damage to the engine block. If your radiator isn’t in the best condition, you may want to invest in a cooling system flush first. It can get rid of any unwanted dirt particles and prepare the system for repair. Of course, you’ll also want to make sure that your engine and radiator are completely cooled before doing anything.

Q: Do radiator stop leak products work on all types of damage?

Radiator stop leaks are designed to worm on minor leaks. Some may also help to improve moderate leaks. However, significant damage cannot be fixed with a stop leak product.

Q: How long do these products take to work?

It may take several minutes for the product to plug leaks and holes. Once you have added it to the radiator, you need to turn the engine on and let it run for a few minutes. This circulates the product so that it can cover the entire system. You may also want to top off your coolant to ensure that your engine has all the support it needs to stay in good shape.

Q: Are radiator stop leaks a permanent fix?

Most radiator stop leaks are designed to be a tempory solution. They can buy you time before you make your way to a professional auto shop for detailed repairs. With that being said, sometimes, a radiator stop leak product is all you need. It’s not uncommon for drivers to forgo costly repairs if the stop leak provided a solution to a very minor damage issue.