Steel Seal Head Gasket Repair logo

How to Use Steel Seal


Head gasket failure is a symptom, not the cause of overheating. The original source of cooling system failure, if still present, must be repaired before attempting to repair your head gasket.

Steel Seal is not compatible with all types of coolant formulation

Therefore, for best results, coolant should be temporarily drained and replaced with fresh water. Once repaired, drain Steel Seal from the cooling system and replace with 50/50 coolant or your usual antifreeze of choice.

WATER IN OIL If water is present, you must change the oil and filter before proceeding. Change oil and leave one quart low. Add last quart after the repair is complete.

Recommended Doses

Anytime you are unsure regarding how much Steel Seal your vehicle requires then contact our tech team on

The Treatment

1. Pour in Steel Seal

Make sure the engine is cold and the coolant in the cooling system is clean. Remove the radiator cap and pour the recommended amount of Steel Seal® directly into the radiator. Screw the cap back on. Tip: In vehicles without a radiator cap, Steel Seal® can be filled in via the expansion tank/surge*.

2. Run Vehicle in Idle or drive

If vehicle is roadworthy: Start engine and drive at freeway speeds for 5 to 10 miles, maintaining between 3,000 - 4,000 RPM, then shut off engine.
If vehicle is not roadworthy: Turn heater and fan to maximum. Start engine, run to operating temperature and then run on high idle (1,000 - 1,500 RPM) for 30 minutes . Turn off vehicle and allow to cool completely.
Warning: Monitor the temperature throughout the application (see engine temp gauge on dash) and if at any point it threatens to overheat, shut it down immediately!

3. Drive Away

If necessary, top up with fresh coolant up to the specified mark on the coolant reservoir. Simply leave Steel Seal® in the cooling system and continue driving your vehicle as usual!

Additional STeel Seal Directions

We want to ensure you have the absolute best chance of success when using Steel Seal and following some of the steps below will increase your chance of a successful repair.

Sufficient Room

*If you are introducing Steel Seal via an surge / expansion tank please make sure that there is sufficient room for Steel Seal to go directly into the cooling system and that it does not just sit in surge / expansion tank reservoir.

Don't mix Chemicals

If you have tried to repair your head gasket with other products, you must flush your cooling system out before using Steel Seal with clean water after disconnecting bottom radiator hose. Because Steel Seal works using a thermochemical reaction and not just by blocking  the crack or hole (and who knows where else), any chemicals that are not supposed to be in the cooling system could negatively impact the treatment. This is why we also advise not to use a flushing agent and only perform a cold water flush. If you have flushed system reconnect bottom radiator hose

Recommended Coolant

Prestone Low-Tox—– (Propylene Glycol pH 8-11) — Biodegradable/non-toxic coolant

Prestone conventional green antifreeze – (Ethylene Glycol— pH 8-11) Low solvent effect, silicate stabilizers and high pH provide the best protection


These directions are for people that have a lot of back pressure building up in the cooling system, usually shown as bubbling in the header tank or air forcing past the coolant cap.

  • Locate the cylinder causing the bubbling in the overflow tank or backpressure. (Remove plugs one at a time till bubbling stops)
  • Before starting the engine, remove the spark plug or injector from the cylinder that was causing the bubbling in the overflow tank or back pressure. If accessible, remove injector wire from that cylinder. This will limit the amount of unburned fuel going into the combustion chamber.
  • If you cannot find the spark plug/cylinder that is causing the back pressure, run the engine with the coolant level down to the top of the radiator core and with the radiator cap off or leave the expansion cap off the expansion bottle with water only just visible.
    Make sure to run the engine up to temperature with the spark plug/Injector out and for the one final time with the spark plug/injector back in place.

Remember you have experts on hand

We are always happy to help and if you have any questions or concerns reach out to the Tech Team at