SKU: 41111

41196 RESULTS Icons2

  • Stops Leaks
  • Repairs
  • One Step, Easy to Use
  • Safely Seals Gasket Leaks
  • Antifreeze Compatible Sodium Silicate Formula
  • Quickly Stops Coolant Leaks

Rislone Block Seal Head Gasket Fix is the easiest solution to stop head gasket coolant leaks. No draining of the cooling system is required. This formulation contains a combination of antifreeze compatible sodium silicate sealing liquid and various size gasket sealing particles which penetrate gaps and cracks and harden to permanently stop leaks. Rislone Head Gasket Fix seals because of the extreme heat inside the combustion chamber (2760°C) which works as a catalyst to permanently harden the material to make it stronger than the actual head gasket itself.

Your vehicle is a good candidate for this product if it can idle for 20 minutes without overheating or having to add coolant. Use on ALL water cooled petrol and diesel engines. Heavy duty formula works on aluminium and cast iron heads & blocks, along with sealing all other engine cooling system leaks better than traditional stop leak products. Rislone Block Seal Head Gasket Fix repairs head gaskets, cylinder heads, intake gaskets, cracked blocks and welch plugs.

Use with ALL types of 50-50 mix antifreeze including conventional green or blue (Silicate-Based) and extended life red/orange or yellow (OAT/HOAT) coolant, and/or water. Suitable for use in petrol, diesel, turbo, LPG and racing engines.


Your engine creates up to 2760° C of heat within the combustion chamber. Enough heat to melt the entire engine in less than 30 minutes! Approximately one third of fuel’s energy is converted into usable power to propel the vehicle, one third of the energy is dissipated out through the exhaust system, and the remaining one third is carried off by the cooling system.

Coolant, which is a mixture of water and ethylene glycol (Antifreeze), is pumped throughout the engines water jacket drawing heat from the head, pistons, combustion chambers, cylinder walls, valves, etc.

The heated coolant travels from the water jacket through a radiator hose, to the radiator, where aided by a fan, its air cooled and returned via the other radiator hose to the engine. Fuel is SAVED and engine life INCREASED when the cooling system quickly reaches and maintains a very narrow operational range regardless of outside temperature extremes or engine load demands. Upon engine start up, the temperature must rise quickly, and then remain balanced – not too hot and not too cold! It’s important to understand how the condition of the coolant and the condition of the cooling system components can affect the operational economy and life of your engine!


  • Allow engine to cool. Make sure engine is cool enough so radiator cap can be safely removed.
  • Shake well. Pour HEAD GASKET FIX directly into radiator. If using in a small cooling system under 5.7 litre capacities, such as 4 cylinders with no air conditioning, install ½ bottles. Tip: If direct access to radiator is not available and if overflow tank is pressurized, you can install in tank.
  • Fill radiator and overflow tank to proper level and reinstall radiator cap.
  • Start engine.
  • Turn heater on hot and fan on high.
  • Idle engine for 15 minutes.
  • Allow engine to cool so cap can be safely removed. 
  • Top off radiator and leave Rislone HEAD GASKET FIX in cooling system for continued protection. Drive vehicle as normal.

Cooling systems that are dirty or partially clogged should be flushed before usage. Protect from freezing. Protect bottle from freezing.


Can Rislone HEAD GASKET FIX be installed in existing antifreeze?
Yes, it is compatible with ALL types and brands of antifreeze including conventional green or blue (Silicate-Based) and extended life red/orange or yellow (OAT/HOAT) coolant. Also works in systems containing only water. Systems that are dirty or partially clogged, a flush is recommended before use.

Can it be installed in a diesel engine?
Yes, it works with ALL petrol and diesel engines. This heavy duty formula works on aluminum and cast iron heads & blocks, along with sealing all other engine cooling system leaks better than a traditional stop leak. This includes repairing head gaskets, cylinder heads, intake gaskets, cracked blocks and freeze plugs.

How does this type of product work?
This formulation contains a combination of antifreeze compatible sodium silicate sealing liquid and various size gasket sealing particles which penetrate gaps & cracks and harden to permanently stop leaks.

What if I don’t have direct access to the radiator?
If direct access to radiator is unavailable and if reservoir / overflow tank is pressurized, you can install in tank. Otherwise remove top hose where it connects to the top of the radiator and install product in hose. Reattach hose and tighten clamp.

Does Rislone HEAD GASKET FIX permanently repair leaks?
Yes, it is a permanent solution for your cooling system leaks. What do we mean by permanent? It is not designed to be temporary, or a quick fix like other brands. Just like replacing a head gasket will not last forever, neither will Head Gasket Fix. Millions of bottles have been sold since the product was developed in 2004 successfully sealing leaks for many years and tens of thousands of kilometres.

Do I need to drain my radiator after the leak has been repaired?
No, top off radiator and leave Rislone HEAD GASKET FIX in cooling system for continued protection and drive vehicle as normal.

What are the dosage recommendations?
One 680g bottle treats cooling systems from 5.6L to 15L. Use 1⁄2 bottle for smaller cooling systems from 3.78L  to 5.5L For larger systems use 1 bottle for every 15L

I accidentally added the Rislone Head Gasket Fix into my fuel tank, what should I do?
Rislone Head Gasket Fix is only designed to be added to the cooling system. If the product is installed in the fuel tank, the tank should be removed and cleaned out by a professional mechanic. Do not start or drive vehicle.

I accidently added the Rislone Head Gasket Fix into my engine oil, what should I do?
Rislone Head Gasket Fix is only designed to be added to the cooling system. If the product is installed in the engine oil and the engine has not been started, in many cases you can remove the valve cover and drain the oil leaving the drain plug off. Then use an engine flush washing out the head keeping special attention to the oil return holes that run down to the oil pan. Clean these out and pour the engine flush down these holes flushing everything into the oil pan and out the drain hole. If the engine has been run, you need to take the vehicle to have a professional mechanic evaluate what can be done to clean the inside of the engine. This might include taking the engine apart to clean all of the parts.

Will Rislone Head Gasket Fix plug my heater core?
No, Rislone Head Gasket Fix will not clog your clean heater core, it is safe and effective.

If using Rislone Head Gasket Fix to stop heater core leaks, make sure you turn your heater control to HOT. Some vehicles have a valve that controls coolant flow through the core.

Customer Feedback

May 2022

"My Grandson and I were heading to Palmerston North for the superstock teams champs in my 93 Chevy pickup. Got as far as Ohakune and found we had a blown head gasket. Well that’s what we presumed it was as the engine overheated and the radiator was empty and there were no visible leaks. Tried filling it with water but it was so hot we had to wait a couple of hours for it to cool down. When we did finally get some water in it the motor sounded terminal. We ended up renting a car and leaving the pickup at Ohakune. Came back 3 days later thinking I was going to be in for a big Tow Truck bill to get back to Whangamata.
Guy at REPCO said try a bottle of Rislone Head Gasket Fix.  I was a bit dubious as the pickup had been standing for a couple of days and the sump had filled with water from the blown head gasket so I didn’t think a liquid was going to fix that.... I was so wrong... After changing the oil and adding the magic gunk I was able to drive 400km home as normal. Great stuff! The pick up was going so good that I continued using it every day for 2 months until I finally got round to replacing the head gasket, even though it was still running sweet... So if anyone asks, tell them that Rislone Head Gasket Repair is magic it works real well. Saved me heaps."

Paul Candler
New Zealand


July 2020

"More than impressed by your Head Gasket Fix, put it in my work car ( Nissan Pulsar ) when it was losing coolant and blowing white smoke, overheating etc from a bad head gasket @ 300 000km thinking id get a few more months out of it then scrap it and its now at 353 000ks and still doing 640ks a week with no smoke no coolant loss and no over heating"



April 2016

"I used it on a 94 Toyota Camry V6 which was running on five cylinders and using 2ltrs of coolant each drive. Within 45mins of using the product the car was running like new on all 6 cylinders and there was no more steam vapour from the tail pipe. I'm really impressed with the product and would highly recommend."

Sebastian Duggin

April 2016

"I have a Ford Explorer that I was putting 1 litre of water a day into the radiator & saw water coming out the exhaust. I put a bottle of Rislone in the cooling system & within 30 mins it was fixed. It saved me $1500-$1800 in repairs. I can\'t praise this product enough & highly recommend it to anyone one the same position I was in. Just do it you won\'t be disappointed. Thanks Rislone!!"

Brisbane, Queensland Australia.

May 2015
"I recently used Rislone Head Gasket Fix on my Mazda van which has 500,000 km on it. I was topping up my radiator  coolant every two weeks.Mechanic informed me I have a leaking head gasket and it was an expensive fix.I purchased yr product 4 weeks ago and since then my coolant level has not dropped at all.Very impressed with your product."

Dave Cleaver

"This may interest some. I have a race engine in my boat and for a while I have been noticing coolant coming out the exhaust pipes on start up for quite some time. Since I only race this boat 8 times a year it doesn’t need high maintenance after each race, however recently the water leak was getting worse to the point it could lock the engine. This is when engines can become very damaged. To give you some idea a refresh or rebuild can cost around 30k and this is done around every 3 years or unless warranted to be done earlier. To cut a long story short after crack testing the heads hot under pressure we didn’t find any leaks, we changed copper gaskets three times and it would still leak when cold. We pressure tested the coolant system while cold and yes after about hour the system would lose is pressure and more coolant would be in the cylinders. After much careful consideration we put the leak down to the sleeves in the cast iron block leaking at the top, we had three cylinders that were leaking. Since the block is O-ringed and we know that compression was getting into the coolant there were no cracks in the block or sleeves when we had the heads off. With race season already started and we missed the first couple of races we honestly thought that a full rebuild including replacement sleeves was in order. Out of shear frustration I decided to see if there were chemical products that would seal the problem until this race season is over. I did some research on the internet plus also visiting various automotive spare part retail outlets all of them full of advice on the products they carried, the issue was becoming confusing to say the least."

"Finally I sent some emails off to various companies for their advice. Rislone were very responsive in recommending a solution to our problem. So off to Supercheap Auto here in Australia and purchased a bottle of the product that was recommended by the company. Now my engine runs a sealed coolant system via a heat exchanger, I start the engine, had trouble running the engine because of the leaking system, anyhow I managed to get some heat into the system. Turn the engine off removed the radiator cap from the header tank pour the whole bottle in. Restarted the engine. Just for the record my engine has the GM red coolant in it. The following situation occurred, within a minute or two the engine started to rev harder. I started to adjust the idol plus mixtures to lower the revs, finally within a couple more minutes the idol had settled, I run the engine for around 30 minutes then turned it off. The following weekend after not starting the engine for a whole week I removed all the spark plugs a turned the engine over and to my surprise no coolant in the cylinders."

"I have now raced my boat on three separate occasions and after each event about week later I have checked to see if there is any coolant in the cylinders and I’m happy to report so far so good. What actually amazed me even more is that it sealed the leaked under compression, normally this would be very unsuccessful as it is very hard to seal a leak whilst high compression is there. We have three more races to go and I will be very happy to report the outcome at the end of the season. I have since told various racers about this and strangely enough two others have used the Rislone products (Rislone Block Seal) to seal radiator leaks in people cars that have broken down on the side of the road with good results. I would like to thank the customer service department at Rislone for their support and reponses to emails in short time frames. I’m more than happy to recommend their products in the future if people should ask. Just to add I ‘m a fully qualified Mechanical Engineer and would not subscribe to such practices normally however invent of saving face in losing a whole race season a quick fix with Rislone has proven a worthwhile test. The engine will be fully rebuilt in the off season this year but in the meantime we are still racing. This engine runs 195 psi cylinder compression cold and leaked down is never more than 6% otherwise a rebuild is in order. After testing the engine after the last race the 2 above figures are not a problem now the block has retained a seal thanks to the Rislone product."