Best Head Gasket Sealers: Permanently Solve Coolant and Engine Oil Leak Problems

Permanently seal cracks and coolant leaks with our top picks for the best head gasket sealer

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A blown head gasket is one of the biggest nightmares a car owner has to face. It leads to other problems such as coolant mixing with oil in the engine, engine misfires, and oil leaks. To effectively fix the blown gasket, you have two options; you can either change the head gasket completely or take advantage of the affordable head gasket sealers available in the market. Since there are many products from different brands, read through our review to find out the best engine head gasket sealer for your blown gasket or leakage problem.

  • Best Overall
    Steel Seal Blown Head Gasket Fix Repair Sealer  
    An easy-to-use product that works well with both diesel and petrol engines. It’s a multi-use sealant that solves problems associated with head gasket leaks, heater core, and freeze plugs.
    Easy to work with. Helps eliminate overheating problems. Improves vehicle mileage. Reduces smoke emissions and oil consumption. Works well for old trucks that cannot hold water. Backed by a 100 percent money-back guarantee.
    Expensive. Will only work well if you flush the engine first.
  • Best Value
    K-Seal ST5516 HD
    An affordable sealant is known to solve common problems fast and blends easily with antifreeze. Can eradicate tapping or flushing and repair other problems such as freeze plugs, heater cores, warped gaskets, and cracked heads.
    A permanent solution to coolant leak repairs. Mixes well with all antifreeze. Doesn’t require engine flushing or draining. Fixes multiple problems. Comes with a friendly price tag.
    Sealant might not work well if the head gasket has extensive damage.
    Discolors some brands of antifreeze.
  • Honorable Mention
    BlueDevil Head Gasket Sealer
    A head gasket sealer that is compliant with ASTM standards and permanently seals the blown head gasket on all types of engines. The sealer is safe and easy to use.
    The sealant is a permanent solution that works well during any weather condition. Prevents coolant leaks. Prevents the loss of radiator fluids.
    Helps with resolving flashing MIL and cold start rough idle.
    Manufactured by a reputable company.
    You may have problems with the thermostat after using the product. May block the cylinder tubes and passages

Benefits of Head Gasket Sealers

  • Fix leakages in blown head gaskets. A blown head gasket is a big problem especially when you are traveling. Most people would opt to have a professional look at the head gasket, and that would translate to wasting a couple of hours as the issue gets fixed. With a high-grade sealant, you could permanently stop the leakage and prevent your engine from misfiring. 
  • Save money. Head gasket sealers are not as expensive as having the head gasket completely replaced. A replacement would require you to buy the head gasket, and you would also have to pay the automotive mechanic that handles the task. A head gasket sealer is an inexpensive option that provides a permanent solution, just like the replacement.
  • Multi-purpose product. A good gasket head sealer will not only help solve issues related to the head gasket; some of these products can be used on other leaks that might affect the performance of your engine. A high-grade sealer can also help solve problems related to the heater core and bad freeze plugs.
  • Time-saving. Unlike completely replacing the head gasket, using a sealant is an easy process. You just pour the sealant into the radiator cap, and it flows through the entire system discovering the leaks. The process is fast, and the leaks will be sealed in under an hour. 

Top Brands


BlueDevil is a company that manufactures professional grade sealants for the automotive industry. The company supplies its products to over 400 distributors located across North America, South Africa, Asia, Europe, and South America. BlueDevil started selling its products in 1997, and is currently headquartered in South Carolina. The company manufactures some of the best head gasket repair additives, and the BlueDevil Head Gasket Sealer is one of its popular products.


ATP Automotive is a renowned automotive products manufacturer who has been in existence since 1955. The company has a 2,000 square foot state-of-the-art facility in Chicago, where it makes top of the line aftermarket replacement parts and car care products for automatic transmissions. Consider trying out the ATP AT-205 Re-seal, which only seals minor leakages in the head gasket. 


K-Seal is an international company that manufactures and distributes sealants around the world. The company prides itself in its ability to sell millions of sealant bottles every year. It’s currently based in New Jersey. The K-Seal ST5516 HD is one of the cheap head gasket sealers manufactured and distributed by K-Seal company.

Steel Seal

Steel Seal is a sealant manufacturing company that focuses on making and selling head gasket sealers. The company has been in business since 1999 and has provided mechanical solutions to hundreds of thousands of mechanics and car owners. Steel Seal is headquartered in the United Kingdom. The Steel Seal Blown Head Gasket Fix Repair Sealer is one of its best head gasket sealants.

Best Head Gasket Sealer Pricing

  • Under $20: This price range includes head gasket sealers that come in small containers weighing under 16 ounces. The content of these containers can help you handle leakages associated with the head gasket effectively, though you might have to get a bigger container for larger engines.
  • $25-$50: If you are looking for a larger container that can fix a couple of leaks, then look into products in this price range. The containers typically have 32 ounces of fluid. That’s enough to handle six- and eight-cylinder engines.
  • Over $50: In this price range, you will find premium products. These are sealers that can fix cracked head gaskets permanently and are from reputable brands. The quantity is also enough to deal with larger engines such as six-cylinder engines and more.

Key Features


The quantity of the sealant is measured in ounces. The quantity ranges from 8 ounces to a couple of gallons. Buy a sealant that’s enough for your problem. For smaller engines, the 16-ounce container is enough to seal a blown head gasket and will allow you to get to your destination. It’s also a good idea to have a small container for emergencies.

Ease of Use

Dealing with a head gasket leakage is as easy as pouring the sealant into the radiator. However, other issues may arise, and you may need to have some technical knowledge of the sealing process. Ensure the product you choose is easy to use and comes with clear instructions on how to seal different leakages.

Other Considerations

  • Type of Engine: The main types of engines are diesel and gasoline engines. These engines might require different types of sealants. When buying a high-grade sealant for your head gasket, make sure you check on the advantages the product has for your engine type.
  • Action Time: After pouring the sealant, you cannot use your vehicle for a certain period of time. You, therefore, need to know how long you have to wait out for the sealant to settle down. Most take about an hour or more depending on the size of your car’s radiator capacity.
  • Functionality: There are products that are designed to solve different leakage problems in the engine. Though you might have a head gasket problem, you can find a sealant that can fix that and also perform many other tasks. Make sure you read the product description to understand what else the sealant can do.

Best Head Gasket Sealer Reviews & Recommendations 2019

Best Head Gasket Sealer Overall: Steel Seal Blown Head Gasket Fix Repair Sealer

Steel Seal Blown Head Gasket Fix Repair Sealer

The Steel Seal gasket sealer comes in two bottles that are enough for people with bigger engines such as eight-cylinder engines. The product comes with easy-to-follow instructions, though you need slight automotive knowledge to use it. This sealer is designed for solving different blown head gasket symptoms, which include white smoke, engine overheating, external leaks, and watery oil.

A unique feature about this sealant is that it’s designed to take care of leaks in older engines with just one application. Also, this sealing agent doesn’t have particles that can build up, block tubes, and lead to more issues in the engine. The fluid will work by bonding to breaches and cracks, even when exposed to high temperatures, and provides permanent sealing solutions. You can expect fast sealing action, and the sealer works well with both gasoline and diesel engines.

Though the sealer is effective, it’s quite expensive. There are cheaper options that offer almost similar qualities to what the product has. You will also have to flush the system before using this sealer. That’s an inconvenience if you don’t have a lot of time on your side or money to buy a new coolant. However, this sealer is a great choice for people with bigger engines, old trucks, and second-hand vehicles.

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Best Value Head Gasket Sealer: K-Seal ST5516 HD

K-Seal ST5516 HD

The K-Seal ST5516 HD is a “shake, pour, and go” head gasket sealer that comes with an affordable price tag. This product’s standout feature is the fact that it’s compatible with any antifreeze product, which eliminates the need to flush out the coolant system before application. It’s a multipurpose product and you can safely use the sealant to solve other leakage issues related to the heater core, engine block, water pump casing, and freeze plugs.

The formula used to make this product uses a type of nanotechnology, which involves microfibers that mesh to seal cracks and leakages. The product is available in a small 8-ounce container that can treat up to 12 cylinders. You can expect to see the effect of the sealant within three minutes of application. The sealant is easy to use and does not need any special skills.

The sealant might be fast but will only work for minor leaks. If you are dealing with extensive damage, you may want to consider a different product. There have been cases of the sealant discoloring some brands of antifreeze products. This sealant is, however, a great choice for people looking for an effective, yet affordable sealer.

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Best Head Gasket Sealer Honorable Mention: BlueDevil Head Gasket Sealer

BlueDevil Head Gasket Sealer

The BlueDevil gasket sealer is an easy-to-use sealer that saves you money in repair bills for your car. It’s a professional-grade head gasket sealer that also solves leakage issues associated with the heater cores, freeze plugs, and other components associated with the coolant apart from the radiator core. As long as you follow the instructions provided, the sealer provides a permanent leakage repair solution. 

You can use this product on gas and diesel engines regardless of the number of cylinders. This sealant has the advantage of making strong bonds with a wide range of materials including cast iron, plastic, aluminum, alloy, and many other types of metals. It also works well on cracked or warped heads, and you do not have to worry about coolant loss or leaks. The product solves internal engine issues for increased mileage.

The main drawback of this product is that it may start to block tubes and passages with some solid matter after some time. This is probably due to the reaction of the sealant when it gets heated up in the chamber. The thermostat may also develop some issues after the sealant is used. You also have to use the sealant with a fresh coolant; otherwise, it won’t work as effectively.

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  • Confirm antifreeze compatibility. There are some head gasket sealers that do not work well with some antifreeze brands. Always check the instructions provided by the manufacturer to see if the sealant is compatible with the current antifreeze brand you are using.
  • If you have a blown out head gasket, you could either replace the entire unit or fix it with a sealant. It’s important to know when to use a sealant product and when to replace the gasket to save time and money. An old and worn-out head gasket will probably not be fixed by a sealant.
  • You should stop driving your vehicle if you suspect that you have a blown head gasket. A blown head gasket means that the oil inside the cylinder and the coolant are mixing, and that will cause the engine to overheat and eventually lead to a misfire.


Q: Are head gasket sealers safe for the engine?

A: Good-quality head gasket sealers are designed to work effectively without compromising the engine. Most sealants have been tested and known to work well with either diesel or petrol engines and with different materials such as plastic, aluminum, and cast iron.

Q: Are head gasket sealers better than complete gasket replacement?

A: This depends on the level of damage you are dealing with. Most head gasket sealers provide a permanent solution to minor leakages. They will, however, only offer a temporary solution to severe leaks, and eventually, you might need a complete gasket replacement.

Q: How long will the head gasket sealer last after application?

A: Different brands have different qualities and while some will last long, others will not. It also depends on the severity of the damage to your head gasket. Most sealants offer permanent solutions to minor leaks but can only last for a maximum of six months if the damage is severe.

Q: Will the sealant clog other holes in the system?

A: Sealants are designed to fill up small holes in the head gasket. Most, however, can also clog up leaks in the transmission, power steering, and hydraulic systems. If you are dealing with bigger holes that the sealer cannot handle, you should think about replacing the head gasket. 

Final Thoughts

The Steel Seal Blown Head Gasket Fix Repair Sealer is our top pick for the best overall permanent head gasket sealer. It works well on older and new vehicles and is suitable for cars, vans, SUVs, and trucks.

If your budget is a little tight and you still need a professional-grade sealer, check out the K-Seal ST5516 HD. It’s an affordable sealant that comes with most of the qualities you can find in more expensive brands.

Have you used a gasket head sealer recently? We would like to hear from you in the comment section below.