ST5516 Heavy-Duty Multi-Purpose One Step Coolant Leak Repair, 16 oz, Pour and Go, Mixes with All Antifreeze, No Flushing Required

This stuff really works. Had a minor leak in the radiator. Follow the directions as they were written on container leaked up within a couple of days.. very easy to use

I just concluded a 7,000 mile drive from Georgia to Oklahoma, then to Cali and from there, Washington state and then back to Georgia in my 2002 Chevy Tahoe while hauling a 21' toy hauler heavy laden with toys. My Tahoe has an aftermarket radiator that produced a pinhole leak during travel. I couldn't directly locate the leak nor was I able to just replace the radiator as I was traveling. So I considered using a radiator stop leak but hesitant to do so as I didn't want to plug up my cooling system at all. I found this product and due to the reviews, decided to try it. It worked almost immediately after running the engine for a while to circulate the solution. And it still has not shown signs of leaking and no affect of the cooling capabilities either. I highly recommend this product!

I waited 5 days to write this review on my birthday. Mainly because I am so impressed with this product and I didn't know that it would hold. I'm not getting paid for this review and I rarely write reviews. A little history. I own a 2007 Mercedes E-63. This car is a beast and is a joy to drive. The dealership diagnosed a blown head gasket on the car. The report shows coolant mixed with the engine oil. My oil almost looked like a mocha espresso. A very bad sign. The car was immediately overheating. I was adding antifreeze every day. The dealership estimated repairs to start at $15K but could easily rise to $25K. Once the top of the motor is opened up I'm sure they would recommend new cams (4), new cam adjusters and of course new seals. A new crate engine for this car from Mercedes-Benz costs $57,000.00. After carefully reading the directions I added coolant with the bottle of K-seal after shaking it for 1 minute. Then I drove the car normally for 20-25 minutes. The car came up to temperature and stayed there. It didn't overheat! After feeling terribly about having to sell the car as a mechanic's special or donating the car I can instead enjoy driving the car daily. I did end up changing the oil 3 times before it didn't appear to have any more coolant in it. Thanks K-seal!

I saw coolant leaking out the exhaust ,could not find (any or) two adjoining cylinders with problems on a compression test. Changed head gaskets anyway, a head bolt came up with odd rusty pitting on its starting thread- showing the possibility of a bad spot in the block.Needed to use the vehicle and could not guarantee that it needed a full motor rebuild over this. Went on with the gasket change(no obvious problems on the old stock gaskets),the heads were decked,installed,everything went good,and now the leak was milder but still there. Compression test results still looked the same,so I tried K seal. I had tried the copper fleck stuff before on other vehicles not much luck. K seal did the job and no more leak out the exhaust.

This thing saved me thousands of dollars. I thought of taking the time to write a review because this is the best $20 I have ever spent. I actually used it three times already over the course of 2 years. So yes... over time I think you will need to use it again. In my case it took about 5-7 months before the coolant started leaking badly again. Then I purchased another bottle and it did the job again for my 04 dodge ram 1500. And again for a third time, which I used a month ago. Not only it sealed the leak, again, not 100%, but good enough for the engine light to go off, and i was able to pass inspection twice. Before i used it for the first time, my truck was about to give up after 3 years it was leaking from coolant to engine (mixing with the engine oil). The only solution was a rebuild or get a new engine that would cost over $3500. It is a great product. Not perfect, but if you have an old car with a leaking coolant system, and if don't want to start spending thousands of $, this is the best product you can find (I tried 2 others before this one, and it was not as good).

It worked! Fixed my Chevy Cruze leak!. Had paid $$$$ to the mechanic with no results...

I used the whole bottle for a small Toyota engine , did not work at all , problem still exist

Good product

So far so good. Seems to work well. Put on 5500 kms and no signs of coolant leak.

I had an unsatisfactory result with one of my cars I earlier reviewed. However, I had a visible gakset leak between the plastic intake manifold and cylinder head in 2007 Town Car, and was about to remove it for servicing until I thought, let me give K-Seal another shot since I had a small quantity left. The result was magic! The leak is gone, and been running dry and clean for a month now.

There was a crack in head gasket of my car and coolant was leaking from there. Results in engine overheating. I added Kseal HD in in coolant and I had driven 5000 KM after that and crack is healed hence no overheating. Authorised service centre had asked to change the head gasket , that could have costed me around Rs. 75000. Local mechanic suggested to weld the crack. That too have costed around Rs. 20000. But Kseal costed me only Rs. 3500. And it really worked for me.

Funciona y es fácil de usar

It s not sealing coolant pump mild leaks.. I can only seal radiator leaks, not in other places- saying by my own experience.. if coolant pump leaks, u better repair it instead of wasting on it..