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NL Head Gasket
repair without disassembly
* in total since 2015; compared to replacing the cylinder head gasket in a workshop.
Not suitable for all types of damage! Quickly check on the order page whether Steel Seal® matches your vehicle’s symptoms.
When to use Steel Seal®
Steel Seal® is designed for typical coolant-side head gasket leaks. Common signs include coolant loss, white smoke from the exhaust, oil in the coolant (or vice versa), and combustion gases in the cooling system. Engine overheating is also common in these cases.
Thanks to its unique thermo-chemical action, Steel Seal® seals leaking areas of the head gasket precisely and permanently—right at the source of the leak. Unlike conventional sealants, Steel Seal® is fiber-free, won’t clog cooling passages, and forms a strong, steel-like seal instead of simply masking symptoms.
Suitable for all vehicles with a water-cooled engine, Steel Seal® offers a fast, cost-effective alternative to replacing a failed head gasket. Trusted since 1999.
Customer experiences with common head gasket problems
Pressure build-up – coolant loss stopped
VW Sharan, 1.9 TDI 96 kW (130PS), year of construction: 2007
Severe pressure build-up in the cooling system and heavy coolant loss (approx. 1 L per 100 km)
After using it as instructed, the cooling system pressure normalized immediately. The coolant loss stopped permanently—over 4 years now, with no teardown or engine work.
BMW 3 Series E46, year of construction: 2005
Oil in the coolant reservoir and elevated pressure build-up in the cooling system.
After flushing the cooling system and using Steel Seal®, both the oil contamination and the pressure build-up disappeared. The cooling system has stayed clean for over 18 months now—with no return of the symptoms.
Oil in the coolant – system clean again
Combustion gases in the cooling system – CO₂ test negative again
SEAT Ibiza, 1.2 Petrol 51kW (69PS), year of construction 2011
Ongoing coolant loss despite replacing the water pump and thermostat. A follow-up CO₂ test in the cooling system came back positive—combustion gases were clearly detected.
After using it as instructed, the CO₂ test was negative again. No combustion gases were detected in the cooling system anymore, and the coolant loss stopped permanently—for 8 months and approx. 25,000 km.
VW T5, model year: 2010
Severe pressure build-up in the cooling system and heavy coolant loss
After using Steel Seal®, the coolant loss stopped. Replacing the head gasket wouldn’t have been economical—Steel Seal® allowed me to drive for over 120,000 km more.
Coolant loss stopped – drove 120,000 km more
Why Steel Seal® is the best option for many vehicles
Save high repair costs
Replacing a failed head gasket is time-consuming. Depending on the vehicle, workshop costs can quickly run into several thousand euros – often regardless of whether additional damage is found. In suitable cases, Steel Seal® provides a functional repair solution without those costs.
99% Success rate
When used correctly, Steel Seal® delivers a permanent sealing result in 98.7% of cases (basis: complaints relative to products sold, as of November 2025).
Fast repair
Steel Seal® can be applied without dismantling the engine. In most cases, the vehicle remains usable throughout. No lengthy workshop downtime.
25 years of practical experience
Steel Seal® has been used worldwide for over 25 years and is continuously refined. Its formulation is based on long-term real-world use in actual vehicles – not on purely theoretical lab tests.
No specialist knowledge or tools needed
The application is designed to be carried out safely even without mechanical experience – provided the instructions are followed.
Award-winning product
Steel Seal® has received awards from well-known automotive retailers and is regularly featured in the trade press – another sign of its quality and acceptance in the market.
Why replacing the head gasket isn’t always the best option
Mechanical head gasket replacement is expensive and – especially on older, high-mileage vehicles – can involve additional risks that are often underestimated. Undetected hairline cracks in the cylinder head or engine block, warped cylinder heads, or extensive resurfacing can significantly increase the scope of the repair and the cost.
In suitable cases, Steel Seal® offers a value-appropriate alternative – without disassembly and without altering the engine’s structure.
1
Pour in Steel Seal®
The engine must be cold. Pour the recommended amount of Steel Seal® directly into the cooling system via the radiator or the expansion tank.
2
Warm up the engine
Set the heater and blower to maximum. Start the engine and let it idle at full operating temperature for about 30 minutes.
3
Drive on with peace of mind
Switch off the engine and let it cool down completely. Afterwards, you can use your vehicle as usual.
- 99% success rate when used correctly
- Easy to use—no tools needed
- Thermally activated sealing
- Fiber-free formula — no clogs
- Proven since 1999
- Free product advice
- 30-day money-back guarantee*
* Money-back guarantee subject to our terms and conditions Section 10 or under Money-back guarantee ).
