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If you use ULTIMATE for a Head Gasket repair and it and it fails to fix the leak get in touch to find out about our money back guarantee. For all our other brands if you have a repair that subsequently fails contact us for a replacement bottle.
Reviews 493
Chris Kitson
Jan 07,2024I have used this product successfully on a previous occasion to plug a leaking radiator on my Vauxhall Zafira with half a bottle. I am now losing coolant and engine oil through a suspected head gasket leak and an additional full bottle has not cured it this time around.
Mr STEPHEN RUSHE
Dec 19,2023Used the head gasket sealer bought from a motor factor and it didn't work despite using a qualified mechanic who recommended it I read the advice on the bottle I went to your website clicking the link got me nowhere as once clicked on the union jack for uk nothing happened Try it yourself
Jeremy Shuler
Dec 12,2023Manifold gasket, 2001 dekota, when I applied it at first it worked for about two weeks, check engine light came on. Took it to the shop they told me it was two gaskets, add another bottle. Check engine went off, haven’t had a problem in about a month now. It works, I’ll keep u updated
Brandon Palmer
Dec 11,2023Originally purchased k-seal ultimate to fix a potential head gasket leak, gave the stuff a chance to work some magic and it improved the Performance and issues with my vehicle, not 100%. I got in contact with the customer care team, very quick to response and very helpful, quickly sorted me another bottle to hopefully fully fix the problem. I would recommend this product to anyone who may have a potential head gasket issue before paying out £1000s even as a temporary fix. It has not caused any clogging issues with my car either.
Christine Nguyen
Dec 09,2023i was so excited when O Reiley auto store clerk recommend this product. I bought and used it as direct. After use, I could drive my car longer before the temperature gauge raised to Hot. I emailed K Seal and asked how often can I use their product or can I use other head gadket leak repair brand? no response yet. Yesterday I saw a puddle of oil or coolant leak under the car. I thought it was coolant since i just refill it. This morning I brought my car to Honda dealer for airbag service. They told me my 2005 honda civic leaked lot of oil. I brought my car to an independent auto repair, they told me i have a major oil leak and all oiled related gaskets, radiator and water pump need to be replaced and estimated repair cost is between $1000 -$1500. I know my car has head gasket problem and hope K Seal will repair it but now i have $1000+ in repair for oil leak plus $1200 for head gasket repair. I am so sad. Before using K Seal, my car had no leak. Its temperature gauge raised hot when driving for 15 minutes soI took it to inspect why. Auto repair shop told me head gasket leak.
Anjie B.
Dec 09,2023Well, it works best for small gasket leaks, is my opinion and experience. If you have a larger leak, this just may not be effective and you will know you have deeper mechanical issues seeing when this won't help you much after using it. It is also just a band aid - and not a cure all, so don't think it's actually like having a real "repair".
Chris
Dec 08,2023Man I have tried just about every seal and leak fix they have out there for radiator systems and none have ever worked had better results with glitter. But I tried this stuff and OMG it really works and fast too I couldn't believe it how well it does work and I am a mechanic and been doing this work for years and couldn't believe how well it works definitely recommend trying it out. I drive a Nissan frontier 4x4 with the 4.0l motor and it sealed up my heater core perfectly.
Andrew Bird
Dec 07,2023Very good product but, if you know where the problem is change the part, It was used on a toyota avensis top hose problem. But the problem still needs fixing hose, 70 pounds. Change it there are limits to a product. If you intend to go on a 7,000 miles trip change the part you idiot.
Amanda Ellis
Nov 30,2023Was recommended k seal after developing a coolant leak. Used as directed and then heating stopped working. Took it to garage who said although it had sealed the leak in the coolant tank it had also blocked other places in the cooling system, it's now going to cost me 200 pound to have the entire system flushed to get rid of the kseal out of it (if that works 🤞) moral of the story - go to a reputable garage and let them fix the problem (which would have prob been not much more that I paid for k seal and 2 bottles of coolant) and avoid further more expensive issue's
Jeffery Dawson
Nov 25,2023This product is awesome it saved me a lot of work from replacing my heater core I got one bottle and the crack was too big and they sent me a replacement one and it sealed it all the way up they back up their guarantee and everything it's definitely worth buying
Bruce Vandusen
Nov 23,2023My 1997 BMW Z3 Roadster was losing about 1 ounce of coolant every 300 miles. I couldn't find the leak. At the repair shop they found the radiator had small leaks. This is not unusual for this model BMW. They replaced the radiator and pressure tested the system. They assured me it was corrected. However, the car continued to lose coolant at the same rate. I had the car pressured tested again. No leaks detected. I added K Seal per the instructions. The car has not been losing any coolant for about two weeks and over 400 miles of travel. I'm keeping my fingers crossed that the K Seal will not damage any other parts, as I had recently installed a new water pump, thermostat and radiator hoses.
A.J.
Nov 20,2023Right out of the blue I had the low coolant warning light come on with my BMW X1. I pulled over to check this out and saw was a pretty good sized puddle under the car. I pulled into the next parking spot and within a minute I had another puddle, a big leak indeed. I was only about 3 miles from home so I got a delivery service to bring my a bottle of pre-mix and filled it up, I had to stop halfway when the coolant light came on to top it off again and the light came on again as I’m pulling in, it saved me a tow but this was really spewing out and had used almost the whole bottle go drive 3 miles. Just from the way it spewed out while driving and where the leak was, where the water pump is, I figured that was it, and when I took it in to the repair shop which is luckily only half a block away they told me the water pump has to go. I had ordered a bottle of K-Seal the night before and the garage told e to come back in 3 weeks because they are all booked up, so I started thinking of using this to get by until then perhaps and still let me drive my car. I did a lot of research on this and in the end I decided against it and wanted to explain why. I’m going to say that there may be a time and place for this stuff but this is more like a Hail Mary pass and even though the repair will cost me $1600 CDN I’m not really going to be able to avoid this nor do I really want to. Water pump coolant leaks are pretty challenging as this is a moving part but there is also the concern that the pump may have and probably has failed and if you slow down or stop the leak the damage that caused it may not allow the pump to do its vital job, leading to much worse consequences. Still though, I at least considered putting this in anyway as it is going to cost me a fair bit of money in taxi fares while I wait for them to fix this, which I then weighed against the risks. I read every post on this site and also looked elsewhere and while it may be assuring that the particles are small enough to pass through, an uncomfortably high number of users reported this clogging up their rads and heater cores and the stuff seems to have a tendency to coagulate in at least some cases, perhaps being exposed to higher than normal amounts of heat, and I never drive more than 5 miles at a time so while I barely get the thing up to operating temperature, this process was.still too much of an unknown to risk doubling my repair bill or worse, People have found pea sized clumps of this in their coolant systems, and telling us that each particle is too small is of no solace if enough of them clump together to form clogs. Still though, I understand that if you can’t afford to fix your car or it doesn’t make sense to then throwing the Hail Mary may be the only good option. I’m actually keeping the stuff in case I ever get to this point and this is surely the only product I would ever use if it ever gets to that. I wanted to share this to emphasize how important it is to think these things through even though k-seal is dirt cheap and only cost me $32 to have this on hand. I would have liked to see the company address the concern of clogging though beyond just saying the particles themselves are too small, and perhaps better advise on which situations may elevate this risk, rather than just going into denial every time. This does not bring comfort to those who are concerned about such things.
Kokulan Sarma
Nov 16,2023Hi guys this was recommended by so many friends. I have Toyota Sienna 2014 only driven 130K and it has minor leak (like 200 ML for every 400KM). ordered this already. wondering how to add(coolant reservoir ?) I have to wait until this goes down?
Johan valdez Gonzalez
Nov 15,2023I haven’t tried k seal but I will definitely try the ultimate one. Please give me any advice. My problem is that I have small particles of oil on the reservoir I will flush out the coolant I will top off k seal ultimate and fill the reservoir with coolant and let it idle. Can you guys recommend me to do it or pay for engine replacement
Herbal Harp
Nov 09,2023Bought a bottle after doing some research, no idea where the leak was from but it wasn’t the hoses. Filled up coolant to correct level and put a bottle in as recommended (shake first) and currently on day 4 with no issues. Was losing about 500ml of coolant a day and now the levels stable. If this sealer lasts I’ll come back and change to 5 stars. *EDIT* about 2 weeks ago having cooling issues. Water raises in the coolant reservoir and leaks from the top. First thing mechanic asked was if K-seal had been used. Has said that K-seal has caused a blockage and parts will need replacing. It’s alright if you’re in an emergency tbf but other then that best to stay away.
Bill Brown
Nov 05,2023I was 150 miles from home when the 3.5L Ecoboost in my F150 developed a coolant leak. The leak was almost a steady stream coming off the skid plate. I was freaking out as it was a weekend and no one could even look at my vehicle until Monday. I looked online and saw K Seal and after reading reviews decided to give it a try. I went to a closeby O'Reilly Auto Parts. Only needed one bottle for the Ecoboost. Followed the directions and then slowly drove around the parking lot until engine was up to temp. Got out and rechecked the expansion tank and saw the level of coolant was stable. Hit the freeway and drove highway speeds the entire way home with no issues. Temp remained constant as did the coolant level. Great product!a
Andrew
Oct 24,2023Long story short I’d been unemployed since 2021. So I hustle doing any kind of job, from fencing to electrical so I need my old 1999 GMC Sonoma to bring income that at least pay for the bills It’s been hard and when the cylinder head of my truck cracked, which I replaced like 4 years ago, I literally cried. Researching K-Seal was the one with most success stories and more affordable than others, I told my wife I will need a miracle or easy $1k in parts and any other damage that the block could’ve suffered. The miracle happened, I was skeptical cause the leak was bad trying to turn the engine on once and the spark plug well will fill with antifreeze. I poured K-Seal on the radiator crank it on, one minute of the engine stalling and suddenly, the miracle.
MDN
Oct 22,2023It work stopped my leaks and saved me a large amount of money for repairs whoever created this product is a damn genius thanks so much. 10/23/2023 the next day my car started back leaking and in the same position so I may be something too hard for k-seal to handle. Doesn’t mean it doesn’t work because there’s too many people saying it does.
Randy M
Oct 19,2023The previous owner of my truck had bypassed the heater core, because it leaked( really bad, as I found out today ). I decided to try a sealant, instead of spending 10 or 12 hours replacing the heater core. I did some research and read lots of reviews and decided to try K-Seal. I hooked the hoses back up, and poured about 1/2 of the bottle in the radiator. It leaked really bad, for about 2 or 3 minutes. Then the leak changed to a steady drip. After the thermostat opened and the coolant started circulating, it stopped dripping, and I was able to pour the rest into the radiator. After getting the air out of the system, I ran the truck about 45 minutes. No leaks, no drips, and GREAT HEAT. I was kinda skeptical before I tried it, but not any more. I will recommend K-Seal to anyone with a leaking heater core. I can't comment on any other leaks, as I didn't have any. But, so far, it is truly awesome! I'll add an update after a while, to see how long it lasts. (I have a Degree in Automotive Systems Technology, formerly ASE certified, 20+ years experience)
Andrew Miller
Jan 18,2024Just used a bottle of HD! Always the same result and response from truck owner! Coolant absolutely running out of a radiator, due to the part being curbed heavily. Low truck or mental driver!? I like to get as much heat in the Coolant as possible as I was always told it aids repair. No time really on this occasion, just bunged it in the header. Driver looks on with pessimistic grin. About 1 minute in and a wee trickle was left but it soon dried up after another 30s. I always enjoy just sticking a bottle of coppery stuff in and sitting back to keep me in a job one more day! Also watching the disbelief in the onlookers. Sometimes it's not that dramatic but I have never been let down by this sealant. Again there's a limit to its powers, if you attend a breakdown where you have to search for pieces of Coolant system and engine block I'd save the bottle for another day. As for clogging up tight areas, I worked for JCB. The 444 engine, we were told, had so little tolerance for Coolant transfer that any sealant wouldn't be possible. I tried it on a test engine in our workshop and had no issues at all. However, I'm only speaking from personal experience and I went steady as I poured. Anyway I'm a fan and will continue to enjoy using K-Seal. I always recommend it to people in the trade.