Prestone AS145 Stop Leak Repair for Radiators, Heater Cores, and Hoses, 11 oz., 1 Pack

Was very reluctant to try this but figured a major player in the coolant industry wasn't in the business of ruining engines so we took a chance and put two of these bottles in a fairly large cooling system. Four months later we've not added any coolant and are not experiencing any issues. A $25 investment in this Prestone product has so far saved us $1300 for a radiator, not to mention the truck downtime as we do most of our own repairs.

When I bought this I gave it about a 5% chance that it actually might work. I was 95% wrong. I had a mystery leak and my system wouldn't pressurize. I added this to my radiator and topped it off with coolant while my engine was cold and drove 2.6 miles to work. Upon arrival I found that my upper radiator hose was hard as a rock and my system was fully pressurized. I wish I could give it 10 stars.

Worked on my truck

Works like it supposed to it sealed up my leak with one application

It took two treatments, but this did what it claims to do: it stopped a coolant leak in on of the hose connections where the system passes through my firewall. It's been a few months (and several thousand miles) since I used it, and the leak has not come back

Had a small leak in the seam of the radiator of my Camry. Stopped the leak. It has been 2 months and is still holding. However, it did also clog the overflow tank hose and had to be blown out to clear it

Tenía una fuga en mi sistema de refrigeración del motor de mi bmw, y les cuento bendito, se desapareció casi al instante, no recomiendo

Well it got me out of a tough spot, had a water pump leaking and going out on the trail. Tried this instead of replacing on the road. Stuff lasted me 800 miles before the Water Pump cracked. Definitely not a long term solution but was able to get me home to fix the real issue.