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

Over the Decades, I've had to make use of a "stop leak" of one form or another.... some work, and others...not so much. I had need to try and at least temporarily... seal up a drip coming from a "new" water pump on my LB7 Duramax powered GMC Sierra 2500HD... about TWO years ago. I found this "K-Seal"..... all I can say is, READ and FOLLOW the specific directions..... and you Will be a "happy camper"!! This stuff Really Works!! If your even thinking about having an engine fluid sealer on hand... just in case, then look no further... this "K-SEAL" truly Does work.

This stuff really works! Had a little Kia Rio that was overheating and misfiring. Found water in the oil when I pulled the dipstick. Ran this through the engine and within an hour it sealed the head gasket and the car is running great now. No more overheating or misfiring at all.

I can’t say it worked 100%. I was not able to have the product work completely into the system to have it work fully. But it did slow down the leak to where I was only putting 1 gallon of coolant instead of 2 gallons of coolant a day into my truck.I end up getting repairs done sooner than I wanted. One of the seals had a crack in it. That’s why it was leaking coolant into my oil.But the stuff gets all through your system, and I had to flush everything out.It did end up in my oil pan. It did not seem to cause any harm to the system at all.It was easy to pour into the reservoir tank.When you look into the reservoir tank, you can see the small particles of copper.It did not seem to cause my heat level to rise either.

Works great

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!

Snake oil. Followed the instructions to a T and this did not work in the slightest. Waste of my money. Do yourself a favor, learn from my mistake, and don't waste yours.

Used it on my 2004 malibu.I used half a bottle.Works great !!! I was shocked.The Car had water squirting out of the tail pipe every time you revved the motor...like alot.I shook it up and poured have into an empty water bottle then poured it into the hose that goes to the overflow. I didn't drain the antifreeze.It worked so fast I didn't belive it...But the car only has 78,000 or so miles so it shouldn't have had any problems that soon.So maybe the hole was small.Either way I'm super happy.3 weeks later it's still going.Oh yeah. And 3 weeks ago I failed my visual inspection while getting it smogged.I'll update ones I take it back.

The stuff worked, stopped the leak. Not sure how long it will last but has been 5 days of driving normally. It was really simple by pouring into radiator!!