K-Seal Reviews 530

TrustScore 4 out of 5

3.8

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Review summary

Created with AI, based on recent reviews

Looking at 23 reviews, reviewers had a great experience with this company. Customers are really happy with the product, often noting its effectiveness in resolving issues like coolant leaks and head gasket problems. Many people mention that the product works quickly, with some seeing improvements within minutes or after a short drive. Reviewers appreciate that the product can fix various types of leaks and that it doesn't leave behind residue or cause clogging in the cooling system. However, some customers were dissatisfied with the product's performance, reporting that it did not fix their leaks or that it caused issues like clogging the coolant system and new thermostats. A few other people also felt that the product was not effective for severe damage or specific types of oil leaks into the coolant system.

What people talk about most

Product

Reviewers mention ambiguous feedback about product. Many customers report that the product successfully fixed... See more

Quality

Customers had ambiguous experiences with quality. Many reviewers reported positive outcomes, with some... See more

Reviews shaping this summary

Rated 3 out of 5 stars

I bought this product a week before Christmas because my car started pressurizing coolant into the overflow bottle and getting hot due to low coolant in the radiator. I never let it boil and had to nu... See more

Company replied

Rated 3 out of 5 stars

First of all. I believe in this product. I went online and read all the usage instructions. I think I have major problems with the head gasket and block after major overheating. This stuff has made... See more

Company replied

Rated 3 out of 5 stars

This is the first part of the review : Today 15/08/2025 I finally managed to buy k seal through Malaysia site and I had to go to get it as it does not sell in thailand . I am looking forwa... See more

Company replied

Rated 5 out of 5 stars

Good product. Worked on a previous car. Recently had a garage put it in my car without warning me. Car is still working but didn't/doesn't have any warning signs of a head gasket. Garage then pro... See more

Company replied


Company details

  1. Car service
  2. Car Radiator Repair Service
  3. Vehicle Repair

Written by the company

K-Seal is the one-step permanent repair for all engine coolant leaks. It could save you thousands in garage fees! K-Seal will permanently repair coolant leaks in the head, head gasket, engine block, radiator, heater core, water pump casing and freeze plug. K-Seal is compatible with all types of anti freeze so there is no need to drain or flush the cooling system. Simply Shake, Pour & Go! With over 12 million bottles sold worldwide K-Seal is the number one bestselling coolant leak repair in the USA and is the choice of leading international roadside recovery organisation to help keep their members on the road. K-Seal has been independently university tested in the United Kingdom to meet ASTM D3147, the coolant leak repair standard. K-Seal is available from all leading auto parts stores and online resellers.

K-Seal Guarantee That a Successful Repair is Permanent.

From a replacement bottle up to a full money back guarantee we have you covered.

From a replacement bottle up to a full money back guarantee we have you covered.
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.

Contact info

3.8

Great

TrustScore 4 out of 5

530 reviews

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Replied to 100% of negative reviews

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Rated 5 out of 5 stars

10/10 Honest and professional

Called K-Seal first to discuss the symptoms and nature of a cracked head pushing exhaust gasses out and the confirmed this product would help as it was not the coolant leaking out within the engine. They could have just sold to me regardless but instead took the time to discuss the problem and the solution forward 10/10 for honesty and professionalism

14 August 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Thank you so much for the review of our Customer Service.

In the replies here, I have always asked that people contact me first so I can offer the best advice.

Even if this means your symptoms are not suitable for K-Seal, I can explain the reasons and state whether a best-effort attempt is still possible.

I was just sorry that, in your instance, this was not the case.

Colin.

Rated 2 out of 5 stars

I have a 2009 BMW X5 3.0 and it…

I have a 2009 BMW X5 3.0 and it initially worked for two weeks. I was sitting in the parking lot of the supermarket and I noticed the engine bay smoking! I bought two bottles of coolant and another k seal. No go this time. I have to get it towed 🤬

4 August 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Dwayne,
Thank you very much for the review. Of course, readers will not be able to gain much insight as there is no discussion of the cause of the coolant leak.
The instructions cover several root causes for which K-Seal is not suitable, and for a repair to fail within two weeks, I suspect we are looking at one of those.
By all means, if you wish to discuss this further to determine why the repair subsequently failed and to claim your free replacement bottle, drop me an email.
Colin.
cbenzie@kseal.com

Rated 1 out of 5 stars

Be careful with this product initially…

Be careful with this product initially it will work. But slowly this makes your car vulnerable. This product blown my head gasket for Ford fiesta and I end up with huge loss fixing the head gasket it’s costing me now 800£ to replace head gasket.

28 July 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Adithya,

As I've mentioned in previous replies, it's always best to reach out to us directly before sharing a negative review. This gives you the power to resolve any issues you may have.

It would allow for a two-way conversation to determine what happened and establish the suitability of using K-Seal, given that you have yet to share any information about the coolant leak other than we were successful.

Our K-Seal ULTIMATE product has a full refund policy, which you have not taken advantage of as this was a Head Gasket issue.

I am also curious to know what "slowly this makes your car vulnerable" means, as this is vague and will not significantly help other K-Seal review readers.

If you wish to investigate this further and find out the root cause, I recommend email myself directly cbenzie@kseal.com

Colin.

Rated 2 out of 5 stars

I was really hopeful that this would…

I was really hopeful that this would work I have a small head gasket leak and with the reviews I was seeing I knew it would work but to my disappointment it wasn’t helpful for me. I’m sure in some cases it might work great as per the other reviews but for me unfortunately it just didn’t happen.

24 June 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi,

Unfortunately, you do not disclose a name. As such, I cannot view any technical communication to see if we could have helped.

Reviewing another person's coolant leak is different from discussing your unique symptoms.

The issue may have been the size of the leak.

Thank you for the review. I would have liked to discuss the solution with you, as we are always here to help before considering any issue as unsolvable.

Colin.

Rated 4 out of 5 stars

Had a gasket leak on the sprinter…

Had a gasket leak on the sprinter popped a bottle in her and BOOM 4 minutes completely sealed then drove 380 miles and not lost a drop - well impressive

13 June 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Max,

Thank you for the review. It's great to see that we could solve your coolant leak in the Mercedes-Benz Sprinter.

Not all leaks are solved this quickly, and it is always worth waiting a week, but in your case, it seems we were super quick.

Colin.

Rated 5 out of 5 stars

I have a coolant leak somewhere on my…

I have a coolant leak somewhere on my insignia I think it's c9ming from a pipe or radiator would k seal solve the problem?

14 May 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi John,

I will need to ask some specific questions before I can answer this.

Please email me directly:

cbenzie@kseal.com

Rated 1 out of 5 stars

Money back guarantee yeah right I try…

Money back guarantee yeah right I try two bottles nothing changed at all had yellow black tag on bottle said money back guarantee send them pictures what I paid for it they just left me hanging didn't back the there money back guarantee at all that's joke people don't believe the yellow black tag on bottle that mean nothing to them at all its just way get your money lot easyer they claim fake lie get people believe in junk

10 April 2024
Unprompted review
Rated 5 out of 5 stars

Bought a 97 Nissan 4×4..

Bought a 97 Nissan 4×4... coolant would just disappear not in oil or coming out exhaust... so I tried k seal...it absolutely resolved the problem within 5 minutes... u can't go wrong with this product!

4 May 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Morris,

I hope you picked up the 4x4 for a bargain, knowing it had a coolant leak, and then saved a fortune with K-Seal. Quite often, we hear of buyers picking up a deal with a known coolant leak, and they already have K-Seal as the solution in mind.

I'm guessing you did not know the leak's source, which is fine because K-Seal will find it, and as you have seen, this can be done within minutes.

Thank you for taking the time to share your experience.

Colin.

Rated 5 out of 5 stars

Vauxhall mokka 1.6 petrol

Vauxhall mokka 1.6 petrol
Had the car for 4 years started using coolant smell of sweet antifreeze when car was used brown gunge in coolant expansion tank and loads of water droplets on internal top surface of coolant tank
Feared the worst last used k seal one month down the line gunge gone droplets gone hasn't used a drop of coolant and no smell of antifreeze
Miracle in a bottle I'd say

13 April 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Nigel,

This is indeed an interesting case study because, on the face of it, oil mixes with the coolant, which is traditionally not an issue K-Seal will solve. That being said, I have discussed many instances of this happening in other reviews here.

You could smell coolant points to an external leak, and K-Seal will be more successful. Add that you waited a whole month before sharing your story, and I am confident this will be a permanent repair.

Remember, we are here to help should the situation change.

Rgds,

Rated 3 out of 5 stars

I bought THE K-Seal Ultimate for a good reason

I bought K-Seal Ultimate about two weeks ago. After extensive familiarization with my vehicles symptoms. I had among other issues come to my comprehension why I would have the best chance of repair using the K-Seal formula that has to do with the distinctly different materials the product uses to close leaks. In my case my oil had become contaminated with coolant. I found THAT this particular K-Seal product allows you to completely ignore the fact that most all the other products with top notch reviews use glass particles, or ceramic to stop the leak. I learned that my vehicles likely problem would have made the mainstreams most popular formulas and process the mainstreams uses that are made up of GLASS fibers (ceramic) that fill in the leak and my understanding is that the type of leak I have will likely not work with that formula. I needed one that stops the leak using a formula without the glass ceramic fibers. I must use an entirely different formula and even then it will be complete "luck of the draw'. The kind and type of leak I have in the engine does not stand a very good chance at sealing using the glass fiber particles. K-SEAL Ultimate Head Gasket Repair has a does have a chance. Hopefully my No Crank No Start issue will be solved this morning and I will finally be ready to use the K-Seal. My vehicle had several problems develop that compounded to to cause my vehicle to become unusable that I had to fix before addressing the leak issue. In Short this review is only part#1. Stay tuned for my part#2 REVIEW. Now to go out and see if my vehicle will finally start so I can use the K-Seal Ultimate. Wish me luck.

30 April 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Tom,

It is challenging to get a review before the product has been used because it does not always accurately account for the repair or our customer service.

While I'm confident in the quality of our product, I want to ensure you're fully informed. In the unlikely event that our product doesn't meet your expectations, there are a couple of things you should know that could be beneficial for other readers of this review.

Firstly, although I cannot think of any reason why this would be negative, our formula does contain micro-ceramic fibres. However, as you state, it is not based on liquid glass technology.

The main issue is that you have stated: "In my case my oil had become contaminated with coolant." We do state in the instructions that K-Seal is not suitable for coolant to oil leaks. However, many examples of K-Seal being successful with these symptoms can be found in the 5-Star reviews.

I shall keep my fingers crossed for part 2.

Colin.

Rated 3 out of 5 stars

Had a small antifreeze leak in cab of…

Had a small antifreeze leak in cab of 2015 nissan frontier that appears to be from the heater core. Put one bottle into my radiator and drove truck for over 30 miles to see if it'd set. Leak seemed to stop for couple of days but now has returned as an bigger leak.

21 April 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Tim,

It would be worth getting in touch so I can discuss the intricacies of Heater Core repairs, as there are considerations to take into account.

Also, please get in touch with the US office, which will be happy to arrange for a replacement bottle as per our guarantee for a repair that subsequently fails.

Thank you for giving K-Seal a try. As I say, get in touch, and a second application may make the difference.

Colin.

Rated 5 out of 5 stars

K-Seal Worked on My Fusion! (Almost...)

I have a 2015 Ford Fusion SE Ecoboost with turbocharger, 92k mi.
I have a very long story over past 3 months of check engine light and #4 cylinder misfire issue that couldn't be resolved. Multiple trips to the shop & diagnoses, $2k spent on new turbocharger, and check engine light still coming on. Bottom line mechanic says engine must be replaced--blown head gasket and/or cracked head. Said $9k to replace engine!!
In desperation I did a lot of research on head gasket sealers, bought K-Seal, put it in yesterday, idled it 25 minutes.
Drove it today. Check engine light went away!! Car runs very smoothly. I will write back in 6 months and let you know how it's going! Thanks!!

May 9, 2024 Update: I haven't been able to start the car for a week. Tried various things, towed to trusted garage and verdict is I need a new engine. Now just trying to get rid of it. I'm not sure if the K-Seal failed outright, or if the existing damage was too much for K-Seal's long-term "reach". At any rate, it was worth a shot.

22 April 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Paul,

Paul, your review is truly fantastic, and I am deeply grateful for the time and effort you put into writing it.

It is far and above the usual "fixed my coolant leak," and not only has K-Seal managed to remove the engine warning light, but it has also saved an amazing amount compared to the mechanic's quote.

It is very easy for a garage to look at simply replacing parts. Still, our philosophy has always been repair, don't replace.

I look forward to the update in six months time.

Colin.

Reply to update May 9th:
It would be a rare instance for K-Seal to fail after this time. Also, a complete failure to start is also unusual for a coolant leak. Email directly if you wish to discuss further: cbenzie@kseal.com
Thank you for the update, I am keen to know more.

Rated 5 out of 5 stars

I was absolutely amazed.

I was absolutely amazed. When the guy at O'Reilly's told me to put the bars leak back and get k seal I was hesitant but I'm glad I did. I didn't know where the leak was but I hadn't looked yet either. When I spotted the leak after pouring it in I said well that was a waste of money. It was pouring out a crack in the bottom of the radiator but to my surprise it actually sealed it. I wish I could post the videos I took

13 April 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Jeremy,

Even if the source of the leak is not found, one of the strengths of K-Seal is that it will find the leak because it is drawn out of that pressure differential spot.

Also, yes, it is pretty deceiving when you see a prominent loss of coolant, and you think it will not work when, in fact, we are successful.

Thank you so much for the positive review. If you can send me the videos, I would love to see them.

Please drop me an email to cbenzie@kseal.com

Colin.

Rated 5 out of 5 stars

This stuff is amazing!!!

This stuff is amazing!!!! I had a small leak in my radiator and it wouldn’t hold coolant I bought this bottle of kseal and in like 5 min the leak was sealed!!! I’ve been driving a lot for 2 days and my coolant is still full and working great!!! This stuff is a true blessing I’m so thankful!!!!

6 April 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Amanda,

Depending on the leak's location, radiator leaks can be troublesome and challenging to solve.

I am confident the leak has been solved, but I welcome you to contact me directly if anything changes.

Thank you so much for the positive review, and I am thrilled you found our product amazing.

Colin.

Rated 1 out of 5 stars

Doesn't work !

3 April 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Daniel,

It is a shame we did not get the chance to help with this coolant leak; as I can see, your email below was sent just before writing the review.

"You product doesn't work.
I will have to use jb weld instead.
Waiste of money I spent"

I would have liked the opportunity to investigate the coolant leak and see if we could have helped solve the issue further.

I think JB Weld is a solution. We would offer QuikSteel as a replacement here in the UK, as it is an Epoxy Putty, which K-Seal is not.

We always try and find alternative solutions when given the chance.

Colin.

Rated 5 out of 5 stars

K seal works

K seal works. Give it a go, you'll be pleased that you did. I tried it with my mechanic's approval. He said it'll work or it won't but it won't clog up anything. Guess what, it worked. My mechanic uses it all the time, with the customer's approval. Can't praise k seal enough.

11 March 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Ian,

Thank you for the positive review; I really do appreciate the time it takes to do this.

K-Seal remains the trade-trusted brand of coolant leak repair products by most mechanics, and many, like your mechanic, use K-Seal.

You received good advice, but if anyone is in doubt, I would be more than happy to answer any questions or offer advice before trying K-Seal.

Again, thank you for the 5-star review.

Colin.

Rated 5 out of 5 stars

Saved me $$$ and hassles of a otherwise expensive repair

I have an old 1977 Aussie Holden. It developed a small leak from the head gasket. My mechanic diagnosed blown head gasket. It was forming only droplets of water but it was consistent droplets developing one after another. I read reviews on multiple products, and also recalled hearing positive comments in the past on Kseal. After convincing myself that the product would not damage anything I decided to try it prior to spending significant money on a head gasket replacement. I added as per the instructions and drove for about 30 mins. Checked still a minor droplet developing. Drove for another 15 minutes,pleased to say fixed. I have waited 6 odd months prior to writing this review in case the results were short lived. However 6 months on, not leaks whatsoever. The reason I have taken the time to write the review is to share with others my successful experience. I am extremely happy and happy to recommend KSeal for like issues.

7 October 2023
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Brad,

It is one thing to take the time to write a positive review, but it is quite another thing to remember to do so after such a long period of time.
I cannot thank you enough for making that effort, as we could quite easily have been forgotten.
Where K-Seal is successful, we like to think the repair is permanent. If the leak should return, do not hesitate to get in touch.
Our replacement bottle guarantees a successful fix for the life of the engine.
Again, thank you.
Colin.

Rated 5 out of 5 stars

2005 Subaru turbo blowing coolant into…

2005 Subaru turbo blowing coolant into the zero pressure expansion tank whenever I fill the system. I'll check after the car has cooled down and the tank is completely full.

Yesterday I needed to make a round trip of about 180 miles along a stretch of interstate with a speed limit of 80 mph, and I drove at that speed.

Upon reaching my destination, which involved coming off the interstate and driving along some 35 to 20 mph streets, I thought I would run the engine at idle for a minute or two to let it settle down, until I looked at the coolant gauge, which was pegged high.

I spent almost 3 hours away from the car, and refilled the cooling system as well as I could, and got out of town before rush hour traffic. Got home, running the heater at full blast the whole time just because. I got home okay, but the coolant reservoir overflowed again.

Today I grabbed a bottle of the standard K-seal at the auto parts store, drove home, let the car cool off for about half an hour and opened the top tank. It still had enough pressure to make me use caution, but it was only air in the tank, I bled the pressure out simply by applying and reducing pressure on the top tank pressure cap.

I removed coolant from the expansion tank to get the level to the "max" line. I used a baster for that, which got me just to the right level.

I burped as much air out of the system as I could with the "gasketed funnel stuck into the top tank and squeeze hoses" method, which got enough to bubble out that I was happy - it's not perfect, but it was good enough.

I then went for a very non-spirited drive for about 50 minutes. I tried my best to stay out of the turbo, and I used every opportunity to engine brake, presuming that it would help draw any coolant into the cylinder past what is clearly a leaking head gasket (it's an 05 subaru, it's never been rebuilt, it's a turbo -- the head gaskets leak, though there is no coolant/oil mixing)

Got home, popped the hood, the expansion tank level had risen about an inch. The distance from the max line to the top of the tank is about 8 inches.

It's hard to argue with the result, though I have yet to do any spirited driving. That can wait for another day. I figure I'll take it pretty easy for the next couple of days, then start giving 'er the beans and see what happens.

At this time I am optimistic that it will hold up against boost, though I am not running a stock turbo or tune, and my boost is set at 19 psi or so --- yes, on an engine with stock internals with 185k miles on it, I know, I know. It needs to be rebuilt, and preferably with some stronger internals.

I guess I got to rambling there, but I am trying to explain. So far I think it worked!

5 March 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Rolf,

What a fantastic and comprehensive review! It offers numerous hints and tips that could be useful to others facing a similar situation.

From bleeding the cooling system of trapped combustion gases to engine braking to help draw K-Seal across the head gasket.

It has been observed that where K-Seal has been successful, the repair holds even with normal engine pressure or extra load from the turbo.

Fingers crossed for you, but do let me know if anything changes.

Colin
cbenzie@kseal.com

Rated 5 out of 5 stars

Thankful it worked!

First, I completely forgot to shake it beforehand (rookie mistake). This was for a '93 4Runner with a badly leaking head gasket. Poured about half into the radiator, and the rest in the overfill. It took about a week I think before it fully sealed, but it did!

1 October 2023
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Emily,

It was brave of you to admit the mistake. I am pleased you continued to add K-Seal to the cooling system and gave our product sufficient time to solve the coolant leak.

Often, K-Seal is not given sufficient time to fix the coolant leak and seal it. If the container is not shaken well before adding, it can take longer for the microfibres to circulate and complete the process.

Thank you so much for taking the time to let us know about your experience.

Colin.

Rated 5 out of 5 stars

Focus loosing water k seal stopped it…

Focus loosing water k seal stopped it brilliant product

5 February 2024
Unprompted review
K-Seal logo

Reply from K-Seal

Hi Michael,

Thank you for your review. Your feedback is highly appreciated and will certainly help other Ford Focus owners with coolant leaks.

Please do keep us informed of any changes in the situation as we are always ready to assist you in any way we can.

Best regards,

Colin.

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