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.

So far its a great temporary fix. I used the K-Seal for my 2007 Honda Pilot EX-L 4WD. For clarification, after having my vehicle pressure tested, and radiator cooling system no leaks were found. But, when a CO2 test was performed to determine if cylinder head gaskets could be to blame for my coolant leak, the test revealed slight CO2 in cooling the system, resulting from possible head gasket failure. So, I'll need to replace head gaskets and recheck cooling system. In the meantime since using K-Seal, the coolant does not appear to be leaking from my radiator and my engine bay has remained clean of any backsplash. Other thing to be noted is that there is a slight difference in the heat coming off the engine as well. So, great value for money, and functionality appears to be working as intended.

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

It actually worked! Our car was approaching 100K miles so i decided to have an oil analysis done. The results, shown in the attached photo showed potassium and sodium in the oil which indicated antifreeze was getting into the combustion chamber and into the oil, potentially caused by a head gasket leak. I changed the oil and submitted a second sample 1000 miles later to verify there wasn't some mistake. after the second test came up positive as well i decided to give K-Seal a try. As you can see there is no longer a presence of antifreeze in the oil and hopefully it stays that way. As PS says, "It could save you thousands!".

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.