Best Head Gasket Sealer for Gas and Diesel Engines

When your vehicle's head gasket gets blown, this can cause many issues, including oil leaks or even engine misfires. Fixing the leakage in the head gasket can even be tricky for your automobile mechanic. To avoid this and further damage to your engine, get the best gasket sealer for your car. Besides, a head gasket sealer is a much cheaper alternative.

Head gaskets are solid mechanical seals used between engine blocks and cylinder heads in machines to stop leakages of gas or fluids while under compression. The head gasket sealer consists of a chemical liquid that flows in the engine to seal the leakages on the head gasket keeping your vehicle in top-notch condition. Although head gaskets are inexpensive, replacing them could cost you a lot.

Many head gasket sealers are on the market, and they don't all provide the best results. It can therefore be hard to choose the best head gasket sealer for your needs. However, it will not be hard anymore; we have a list of the best head gasket sealers highly recommended by auto technicians, drivers, and car owners. Keep reading!

1. Steel Seal 8 Cylinder Engines Head Gasket Sealer

Head Gasket Sealer for 8 Cylinder Engines - Steel Seal
  • Permanently seals head gasket leaks
  • Do-It-Yourself pour in head gasket fix
  • Award winning, triple-patented formula
  • Backed with a 100% Money-Back Guarantee
  • Used for all 8 cylinder engines (2 bottles)

If you are looking for the best head gasket sealer for eight-cylinder engines, we recommend the Steel Seal. This sealant comes in two bottles enough for a car owner with bigger engines like the eight-cylinder engines. The head gasket sealer features easy-to-follow instructions, although you need a little knowledge to use it. Furthermore, this sealant is designed for solving various blown head gasket signs, including engine overheating, external leaks, watery oil, and white smoke.

Steel Seal is also designed to take care of leakages in older engines with only one application. The sealing agent on the sealant doesn't have particles that can accumulate, block tubes then lead to more problems in the engine. The fluid works by bonding to cracks and offers permanent sealing solutions. The sealant works well with diesel and gasoline engines, plus you can expect fast sealing action with this sealant.

Although the head gasket sealer is effective, it is fairly expensive. When applying it to your engine, you will have to flush the system before applying it. It can be inconvenient if you don't have time to go through the process or money to purchase a new coolant. Nonetheless, this head gasket sealant is ideal for car owners with bigger engines, second-hand vehicles, and even old trucks.


  • Ideal for eight-cylinder engines
  • Easy to use sealant
  • Great for both gasoline and diesel engines
  • Effective on old engines


  • Fairly expensive

2. K-Seal ST5516 Coolant Leak Repair

K-Seal ST5516 HD Multi Purpose One Step Permanent Coolant Leak Repair
  • Permanent coolant leak repair - Just shake, pour and go
  • Mixes with all antifreeze
  • No draining or flushing
  • Fixes cracks and leaks in radiator, head gasket, freeze plugs,...
  • If product did not seal head gasket leak, the system might be...

If you are looking for the best head gasket sealer that is easy to use, count on the K-Seal ST5516 Coolant Leak Repair. This head gasket sealer is a "shake, pour and go" product that is easy to apply, plus it comes with an affordable price tag. It is compatible with antifreeze products which remove the need to flush out your car's coolant system before application. Furthermore, it is a versatile sealant, and you can safely use it to solve other leak problems related to the engine block, freeze plugs, heater core, and water pump casing.

The sealing agent uses a nanotechnology formula, which involves microfibers that mesh to seal leakages and cracks. This head gasket sealer is available in a 16-ounce bottle that can treat at least 55 quarts. Besides the sealer not requiring any special skills to apply, you can expect to see it's within minutes of application.

Although the head gasket sealer is fast, it only works for minor leakages. If you are dealing with big damage, you may want to buy a different product. Some customers complain of the sealant discoloring few brands of antifreeze products. Nonetheless, the head gasket sealer is an ideal choice for people looking for an easy to apply yet affordable sealant.


  • Easy to use sealant
  • Come with an affordable price tag
  • Versatile head gasket sealer
  • You don't have to drain the cooling system


  • Discolors antifreeze products

3. BlueDevil Head Gasket Sealer (38386)

BlueDevil Head Gasket Sealer (38386)
  • Good for Head Gaskets, Warped or Cracked Heads, Heater Cores, and...
  • Contains no solid or particulate matter that can harm a vehicles...
  • Alternative solution for costly and time consuming repairs
  • Safe and easy to use
  • Permanent Repair

If you are looking for the best head gasket sealer for DYI repairs, you found one, the BlueDevil 38386 head gasket sealer. This 32-ounce engine and cooling system head gasket sealer come with a radiator flush of the same dimensions. It is one of the few sealers which seals without the need for the addition of particles. After applying, it creates a permanent fix on radiators, leaking gaskets, freezes plus and heater cores, saving you a lot of money from replacing the entire faulty components.

The sealing agents contain a strong chemical weld. With this head gasket sealer, you can do a quick DYI fix on your car's engine. All that is needed of you is to follow instructions. You can easily seal alloys, aluminum, metals, and plastics with this sealant. Additionally, it is compatible with both gasoline and diesel engines of any automobile, plus it doesn't cause clogs in your car's engine.

The process of application of this sealant takes up to two hours of downtime. That is still fair, considering other sealants take up to a day at least. Additionally, in case this sealant fails, no money-back guarantee. Nevertheless, this sealant has an incredible success rate.


  • Prevent the engine from overheating
  • It is a versatile sealant
  • Ideal for DYI repairs
  • Suitable for gas and diesel engines


  • No money-back guarantee

4. Bar's Leak HEAD SEAL Blown Head Gasket Repair (HG-1)

Bar's Leak HG-1 HEAD SEAL Blown Head Gasket Repair
  • Repairs Blown Head And Intake Gasket Leaks
  • Seals Cracked Cylinder Heads And Blocks
  • Stops Heater Core And Radiator Leaks
  • Fixes Leaking Freeze And Core Plugs

With this professional-grade versatile sealant, you can repair the blow head and gasket intake leaks without much hassle. It can easily fix the freeze leaks, fix core plugs, the cylinder blocks and heads that are leaking or cracked can be easily sealed. Additionally, this sealant easily prevents any heat core leak and radiator leak and is ideal for blown head repairs of gaskets.

The Bar's Leak Head Seal Blown head gasket repair is also antifreeze compatible. It doesn't require you to flush the radiator, making it very hassle-free as a head gasket sealant. Furthermore, the total time for downtime and installation is about 45 minutes.

One bottle of this head gasket repair sealer can treat up to 2½ gallons for any car's engine, and for a four-cylinder motor, you require half the bottle. Being an option for repairing coolant leaks where you have to replace the head gasket, cylinder head, or radiator, the sealant is a perfect solution to hold on to. Furthermore, the leakages are permanently sealed with this repair sealer.


  • Offers permanent fix
  • Highly versatile head gasket sealer
  • One bottle has enough sealant
  • Easy to use


  • Not recommended for interior leaks

5. Bar's Leaks Permanent Head Gasket Fix (1111)

Bar's Leaks Block Seal Head Gasket Fix
  • Stops block leaks
  • Seals cracked cylinder heads and blocks
  • Repairs blown head gaskets
  • Contains a combination of antifreeze compatible sodium silicate...

For the best one-step sealant, consider the Bar's Leaks 1111 Block seal Head Gasket Fix. The sealant easily fixes blocks, block leaks, and cylinder heads that have cracked. Furthermore, you can easily repair head gaskets damaged or blown as it is a one-step formula that is easy to use ( about 15 minutes only).

You can easily and conveniently pour it into the head gasket or radiator without the requirement for draining. It offers a permanent solution for head gasket sealing and repair. Moreover, the car can last for 20 minutes without overheating after pouring the Bar's Leaks 1111 Permanent Head Gasket Fix in the radiator.

This sealant is compatible with antifreeze; thus, no worry about putting up with antifreeze compatibility. You don't have to flush the head gasket to pour this sealant. Furthermore, it is perfect for V6 engines and a cheap way to fix your car.


  • Easy to use sealant
  • You don't have to drain the cooling system
  • Compatible with antifreeze
  • Come at an affordable price


  • Can only fill small leaks

Factors to Consider When Buying the Best Head Gasket Sealer

1. Compatibility

One of the essential things you need to check out is whether the head gasket sealer is compatible with your car's engine in the first place. Or else, instead of fixing the problem, you will make it infinitely worse.

 There are sealers designed for diesel vehicles, others for gas engines, and some operate only with water-based cooling systems, though you will also find head gasket sealers that can work with antifreeze.

 2. Functionality

Apart from sealing your car's head gasket and shielding you from leakages and other engine problems, sealers are usually advertised as versatile products meaning they double as permanent or temporary fixes for other engine-related issues.

These include problems with the cooling systems, radiator, cylinder heads, engine block, etc. Perse, you will be saving cash by purchasing a multifunctional head gasket sealer if you want to deal with these issues instead of spending on a solution for every problem individually.

3. Experience

Sealants have different instructions that you should follow before use. For instance, some brands need you to flush out the coolant before pouring in the sealer, while others need you to remove the thermostat then reinstall it back. Consider your ability to use the sealant before buying.

4. Action time

You would want something effective fast so you don't have to be waiting for a long period before you can start your car's engine again and get back on track. Most head gasket sealers take up to an hour or so to completely do their job. It is still crucial to ensure that the sealers work well, although it may take a little more time instead of one that works fast but only lasts for a short time.

5. Ease of use

These head gasket sealers come in various formulations. Some are aerosol sprays, while others are poured in liquids. Furthermore, some call for you to brush antifreeze and other mixtures in your car's engine and cooling system before, while some are just pour-and-go.

If you want an easy, quick and simple solution, grab a pour-and-go bottle of sealers that does all the work for you; furthermore, ensure that it works effectively without you having to do somewhat preliminary steps.

6. Permanence

How permanent the effects of the head gasket sealers are also highly essential. What you are looking for works as a permanent fix instead of one that you will keep applying. Also, it is not like you can effortlessly monitor when it is time to pour in more sealer again since you will only notice this when issues start arising again, and you wouldn't want to wait for that moment.

7. Time to cure

Most sealants have an activation time during which you can't drive the car. The product instructions must indicate the time to cure. Most need about an hour, while others take longer depending on the radiator capacity.

Products like Bar's leak hg-1 sealer takes the least time ( about 15 minutes) to seal the head gasket. Nonetheless, if you are patient enough or have time to wait for the sealer to dry up, don't back away from purchasing sealants that take longer to cure.

8. Quantity of the head gasket sealer

Although the sealant is measured in ounces, it is usual practice for manufacturers to specify the size of the car's engine or the number of cylinders the sealant can successfully repair. With quantity normally ranging from 8 ounces to a couple of gallons, you must ensure enough products to treat your vehicle effectively.

Frequently Asked Questions on the Best Head Gasket Sealer

1. What is the best sealant?

Even though there are a couple of universal solutions on the market, it depends on your case. For instance, K&W's solution is one of the multipurpose products; however, its chemical formula requires extreme care when applying it. If not, ATP's provide works too, unless you are working on a power steering system or transmission.

2. Do head gasket sealers work for diesel engines?

Yes. Normally, anything that is meant for heavy-duty applications. Our K-Seal and Steel Seal entries are perfect for diesel engines.

3. Are head gasket sealers permanent-fix?

Some sealants praise themselves for being a permanent solution, but the majority are not. At times, it is a matter of the application. As with anything, it is important to check what the product is good for.

4. Can a head gasket sealer damage my car's engine?

If not applied correctly, it may lead to a breakdown of the engine's periphery (e.g., cylinder tubes, thermostat, e.t.c), which, if it is left unattended, may lead to disastrous failure down the line.

5. Do head gasket sealers work?

Yes. If applied properly, it should work as described. Ensure you know what the sealant is good for, to you know what to expect.