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How to use Steel Seal 

Blown Head Gasket Repair in 3 Easy Steps...

How to use Steel Seal to fix a blown head gasket


1. Make sure the engine is cold and remove the radiator cap.

2. Ensure there is plenty of water/coolant in the vehicle, but enough room for Steel Seal to make its way into the system. If you need to add coolant, add Steel Seal first and top up with coolant before starting engine.

3. Pour Steel Seal directly into the radiator or expansion tank. Tighten the radiator cap.

4. Turn the heater and fan to maximum. Start the engine and run your vehicle up to temperature (please note this can take between 15-25 minutes depending on the condition of your vehicle). Once your vehicle reaches operating temperature run for 30 minutes.

5.Turn off vehicle and allow to cool completely. Top up with antifreeze/water as necessary, replace radiator cap tightly.

For best results:

  • Unless you are confident that no coolant additives have been used in the past, we recommend flushing the cooling system with clean water.
  • Steel Seal is compatible with most antifreezes, but also works in clean water. We do not recommend using Steel Seal with long life / extended antifreeze. If completing the treatment with water only, simply follow the steps above with plain water and add antifreeze afterwards for best results.

Additional Steel Seal directions for back pressure:

These directions are for vehicles with bubbling in the header tank or air forcing past the coolant cap which could prevent Steel Seal from getting to the head gasket.

  • Remove plugs one at a time until bubbling stops to locate the problem cylinder causing the back pressure or bubbling in the overflow tank.
  • If accessible, remove injector wire from that cylinder. This will limit the proportion of unburned fuel going into the combustion chamber.
  • If you cannot find the spark plug/cylinder that is causing the back pressure, drain the coolant level down just to the top of the radiator core and run the engine with the radiator cap off, or leave the expansion cap off the expansion bottle with water only just visible.

Steel Seal Frequently Asked Questions

When was Steel Seal™ established?

The product was developed in the USA and has been through some very strict independent and laboratory testing. Scott Laboratory has performed a thorough evaluation of both Steel Seal™ and its competitors and found Steel Seal™ to be superior to all products tested. Steel Seal™ has been used successfully in hundreds of thousands of vehicles. Steel Seal has been on the market since the November of 1999. It rolled out by sending 80,000 infomercial-style videos to nearly every mechanic shop in the states. This was followed with advertising in Motor Age, Motor, Underhood Service, Auto Remarketing, Used Car News, Used Car Dealer and Tech Shop. The combined circulation of these magazines literally reaches nearly every shop manager, mechanic and used car dealer in the United States.

What is Steel Seal™ made of?

Steel Seal™ is made of several chemicals that, when combined under the right circumstances, creates a permanent seal as strong as steel. The major advantage of Steel Seal is the durability of the seal. The formula creates a seal that on a molecular level is close to the various types of metals in an engine, so that the seal will expand and contract at a similar rate to the engine. This has led to excellent repair longevity.

How does Steel Seal™ work?

Once the engine is started and reaches operating temperature, Steel Seal™ is distributed through the engine. The product is drawn into the damaged area and seals the crack with a thermo-chemical bonding action process, which happens layer-by-layer for maximum seal strength. This is similar to that of an epoxy resin, just in liquid form.

Will Steel Seal™ clog the engine’s cooling system?

Steel Seal™ is a clear formula that contains no fibrous materials or particles that could clog engine coolant passages, unlike competitor products. You can see for yourself; just look through the bottle.

Will antifreeze compromise the seal?

Whilst it can be used with any 'traditional' antifreeze, for best results we recommend using a good quality 2 year (blue) ethylene glycol antifreeze. We do not recommend using Steel Seal with long life / extended life antifreeze. If your vehicle currently uses extended life antifreeze we would recommend flushing the system and carrying out the treatment with fresh, clean water.

How long will Steel Seal last?

With Steel Seal™ the seal is permanent under normal operating conditions. Remember there is always the possibility of another leak in another part of the engine, but our money-back guarantee can provide an additional bottle of Steel Seal free of charge to make this repair too.

What will Steel Seal™ not fix?

Steel Seal™ will not seal leaks in hoses, seals, water pumps, or extremely large cracks in the head or block resulting in the vehicle not starting. If the engine does not start, Steel Seal cannot work as it relies on temperature and pressure.

Is Steel Seal a scam?

No. Steel Seal really does work, boasting a 99%+ success rate, and we offer an easy to claim money-back guarantee. Please speak to one of our many stockists to see how confident they are in the product, or see our Reviews Page.

What do I do if I have used another product first?

There are several good quality products on the market such as K-Seal, Holts, Radweld and Seal Up, however, they all rely on fillers unlike Steel Seal and can therefore break down. Before using Steel Seal, the cooling system must be flushed thoroughly with water, NOT a flushing agent.

Are there any special precautions I should take when using Steel Seal™?

Steel Seal™ should be kept out of reach of children. Avoid eye or skin contact. Wear gloves/eye protection/face protection. If eyes or skin become irritated with Steel Seal™, rinse with cold water immediately. If swallowed, do not induce vomiting. Call a physician immediately.

How much Steel Seal do I need?

Up to 2.5L engine: 1 bottle
2.5L to 4.0L engine: 2 bottles
Over 4.0L engine: 3 bottles

Does the treatment time vary depending on how many bottles of Steel Seal™ I use?

No, the treatment time for the procedure will be the same regardless of how much Steel Seal™ is introduced. The total number of bottles required must all be added at the same time, and the instructions for the use of Steel Seal™ are the same with the same engine running time for three bottles as there is for one.

(Stockist question)What happens if the retail customer comes back to me to uphold the guarantee?

Simply direct the customer to us, Steel Seal Ltd. Direct either by phone 0871 288 7125 or email We then deal with your customer directly. Should your customer want you to forward their details to us, the same applies.

My vehicle is leaking oil at the head gasket?

Steel Seal will not fix oil leaks, only coolant-related leaks on the head gasket.
A mechanical fix is required to stop oil leaks from the head gasket.

I'm trying Steel Seal for a second time as my car's still overheating, do I need fresh coolant?

If the coolant was fresh and clean the first time you used Steel Seal, you will not need to flush it again. If the coolant has become dirty either with oil or over time, flush it first.

My Steel Seal has a white sediment in the bottom of the bottle, is this still safe to use ?

Steel Seal is absolutely fine to be used in your vehicle, the sediment in the bottle is built up over time as the product sits. Simply shake the bottle before use and the sediment will disappear; this will not affect the functionality of the product.

If you have any questions call 0871 288 7125 (UK)

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Why Steel Seal?

Because Steel Seal simply repairs blown head gaskets, cracked blocks and warped heads and comes with a Lifetime Money Back Guarantee for when in the unlikely event it fails to do so.


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Steel Seal Ltd, Unit 3B Wellington Road, Waterloo Park, Bidford-Upon-Avon, Warwickshire, B50 4JH