K-Seal ST5501 Multi-Purpose One Step Permanent Coolant Leak Repair, 8oz, Pour and Go, Mixes with All Antifreeze, No Flushing Required

I have a 2000 Pontiac Grand AM GT V6 3400 engine, bought the car new from the dealer. A few years back the engine developed a coolant leak in the lower intake manifold, discovered oil in the coolant and needed to fill the radiator tank every couple of weeks. I had a mechanic remove the intake and replace the gaskets; he also suggest I have the heads removed and new head gaskets installed while he had it apart. $1,500 later it was back together and running great, no more leaks. Fast forward about 10K miles and a little over a year later, out of warranty I may add, the engine would smell of coolant and started to leak externally. I was going through a gallon a coolant every couple weeks. Take into account this car has about 100K miles and has a market value of about $1,800. I wasn't going to throw anymore money after bad. So I kept driving it, but one morning I started it up cold and the engine began to miss on 1 or 2 cylinders, the check engine was flashing, indicated the misfiring cylinders. I towed it to another mechanic to see what the cause was, turns out the head gasket was blown this time, compression test proved his theory, he suggested I get another engine from a junked used car and try my luck. That would cost about $3,000 with parts and labor. Not about to throw any more money away, I had the car towed back to my house where it sat for a few months. Not sure what to do with this car, body, paint and interior was in excellent condition, oil was always changed with Mobile 1, it was a well maintained car, was a shame to see it there dead in the driveway. Just had new tires and brakes installed prior to the coolant leak. One day I ran across an article promoting K-Seal, after reading the great reviews here on Amazon, I figured what the heck. It was either call the junk yard and have them pick up the car or spend less than the cost of lunch and give it a shot. Can't believe how easy it was to do, I pulled the radiator hose from the engine block, poured in the K-Seal and reinstalled the hose. The directions state you do not have to drain the coolant like other brands require. Started the car up, and of course the engine was misfiring and check engine light began to flash like before. I let it idle for a few minutes to warm up, when it got to operating temperature, I took it for a drive around the neighborhood. Within about a mile of driving, the engine smoothed out and the CE light went dark. Drove around for another 20 minutes and returned home. I parked the car and check underneath to see if the coolant was leaking like before, to my surprise it had stopped! I let the engine cool and topped off the coolant reservoir with fresh antifreeze until full. I decide to drive the car to work the next day, a 35 miles commute one way into the city, in the middle of summer, ran flawless. Wow! Absolutely no problems since the K-Seal treatment. I have been driving the car now for 7 months and about 6K miles. The coolant hasn't leak a bit and the car runs flawless.Even my mechanic can't believe this stuff actually worked. I am a believer and have since told many people of my experience with this product. Had a buddy with a similar issue with his beloved 2 DR Accord V6, fixed his leak too! I normally don't spend the time to write reviews, but this product truly has made a believer out of me. What do you have to lose? I almost threw away my car, and for a measly few dollars it is now back on the road better than ever. Thank you K-Seal ! I want to add that after reading the one star reviews on this forum that these people were not using the product as intended. It is designed to very small leaks like in gaskets and cracks in the engine block of heads. It needs high heat to cure the fine copper powder that forms a new gasket. If you have a large leak in a radiator, heater core or hose, it's probably not going to work for very long if at all, better off replacing them. Now head gaskets, yes give it a shot!UPDATE: 9/9/16 Still no leaks, I've clocked 20K+ miles on K-Seal with no issues. Hoping for another 20K... buy this stuff.UPDATE: 1/11/17 Well, the engine miss has returned, anti-freeze is disappearing again, head gasket is leaking again. Just poured another bottle of K-Seal in again, within 5 minutes the leak is repaired again. This stuff is great, my old beater is good for another 20K I hope. Money saved again! My mileage on the first repair was 23K miles, not bad for a $11 fix.

K-Seal is a lifesaver! I had a persistent coolant leak, and this product sealed it up quickly—no draining or flushing required. Just shake, pour, and drive! Within minutes, the leak was gone, and my engine's cooling efficiency remained intact.I love its versatility—it works with all types of antifreeze and is suitable for various engines, including light trucks and cars with up to 12 cylinders. The fact that it's backed by professional-grade testing and trusted by mechanics gives me confidence in its durability.If you’re looking for a simple, cost-effective solution to coolant leaks, this is it! Highly recommend keeping a bottle on hand for emergency repairs.

Works as it should, not meant for long-term fix. I bought for a friend with a leaking radiator, and it did stop leaking... for 3 weeks. Great for a quick fix, but not to permanently fix the problem.

K-Seal did a good job fixing a small leak in an old radiator, but did not have any effect on a heater core. Both the core and the radiator are 40+ years old, so I'd say it did a good job overall

I had a little pin hole leak in my radiator on my 2002 VW Passat wagon (130k miles). It was somewhere in the fins so it wasn't something I could do a JB weld fix on. While i was contemplating spending the six hundred bucks in [parts and labor to replace the radiator, i just kept adding more coolant. It wasn't a really bad leak. Mostly just annoying because of the smell of burning radiator fluid. But after about a week, it just stopped leaking on it's own, so I've been driving around town with my fingers crossed hoping it would not start leaking again.But then we had planned a family trip out to New Mexico from KC. It was about 110 degrees F out and 1,400 miles to cover round trip with very long stretches of highway cutting thought the middle of nowhere, with absolutely nothing around for miles, so the idea that the radiator would probably choose this time to start leaking again was a serious concern to me. Yes, technically I should have just replaced the radiator, but instead i decided to just bring a couple of gallons of pre-mixed coolant along and ordered a bottle of K-Seal to take along as a "just in case" precaution. Sure enough about half way out there the radiator started to leak again. This time worse than before. So i carefully followed the directions, shaking the bottle of K-Seal but poured only about half of the bottle into the reservoir/overflow tank (the bottle said it would treat up to 10 cylinders and worked on cracked cylinder heads and engine blocks, so i figured half a bottle would be plenty for a little radiator pinhole)As other reviewers have observed it does come out as a thickish ugly brown liquid that just sits there in the bottom of your overflow tank. Which is admittedly kind of scary, especially if you are skeptical of these products to begin with. But shortly after the car was up to temperature, the leak stopped, as advertised -- even though the k-seal was still very noticeably sitting at the bottom of the overflow tank. VW antifreeze is reddish pink and the K-seal at the bottom was a darker brown. After driving the rest of the way out there it had mixed with the rest of the coolant so it didn't look as nasty in the tank.I've driven another 1600 miles on it and not had any issues. I think the biggest fear with these types of "sealer" products is not that they will not actually seal the leak, but that they will gum up all the intricate little passageways in your heater core, and the rest of your cooling system, but I haven't had any issues at all with this. If I do, I'll be sure to post back and downgrade my 5-star rating.So, I'm sold. this stuff saved my butt and I would definitely recommend it -- especially if you're in a bind. I would never use this (or any other product like this) as a preventative measure like some of the product testimonials on the K-Seal web site, but if you have an older car that you don't want to dump a bunch of money in for repairs, I'd definitely give this a go.

Shook bottle as instructed in directions and emptied into my radiator. Drove ten miles to circulated K-Seal throughout my newly rebuilt engine.It sealed my two weeping freeze plugs that would have been very difficult to change because of their location.

Its a little container, listed like a gallon but its really small container. Im not sure yet how works but I was waiting to receive bigger container.