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

I bought this larger size because I wanted to use it in two different vehicles. I put the majority of it in a vehicle that I needed to add antifreeze every couple days and was blowing white smoke out the exhaust. I no longer need to add antifreeze and there’s no white smoke. The other vehicle I needed to add antifreeze maybe once a week. I added the lesser portion to this vehicle and it is not used any antifreeze since.

The stuff really works. My F350 powerstroke had a leaking water pump after 266000 miles. It was leaking like a sieve. Poured the K-Seal in, leak slowed up within a minute, totally stopped after 5. I totally impressed with this product. I never write reviews, only if the product works better than expected or if the product is junk. 5 stars for K-Seal.

Works as advertised, fantastic product. Succeeded where Bar’s Leaks failed. 1990 F250 w/460 and constant coolant leak front of head below thermostat. Stopped leak within 5 minutes of adding product to radiator. Would definitely purchase again

I bought these to use on my 2011 f350 diesel with a leak on one of the front seals behind the water pump, if I wante to fix it right I would have to take the whole front end of my truck, fan, water pump, and even the front crank cover, no way,, so I bough this mainly because the manufacturer stated that this were permanent, not temporaty fixes, so Bought it, pour just half the bottle and wow! it stoppe, I was impress, but then a cold front arrived and neded to use my heater (wich I just replaced last winter with an OEM heater core) and bam!!! mildy warm air was comming out of the vents, so.... I guess i will now have to replace the heater core wich I can do in about 5 hours (take center console out, and then dash and it literally takes less than 5 minutes to take the old heater core out and put the new one in) I guess is better that taking the front endwhat I would do different now it would be using this product and then cutting my heater core lines and splicing then togheter to bypass my heater core, let this stop leak do the magic and then flush the old coolant, put new one in and then connect back the heater lines

Product works as advertised 👍🏽🏆🔥🔥🔥

it doesn't work, waste of money EDIT: DO NOT BUY THIS PRODUCT!!! IT CLOGS UP YOUR ENGINE AND WILL CAUSE IT TO BLOW UP!!!

Flush cycle and then back in with this product and water and then dump that water out to be able to put coolant back in it to be able to put it back in the service and a you know winter time scenario or summer to Winter scenario this stuff you just poured in and let it do its job and you're done you don't have to drain the coolant out you don't have to go through a big process of it throw it in there let her idle for a while they're back in service and go to work make some money and stuff keeps equipment and stuff operating when you don't have a chance to take it down or take it out of the field for a while and it'll get you by or it'll work as a permanent fix I wish I could get buy stocking in this stuff

i used this stuff for the first time 8mo ago after reading the great reviews. i was blown away as it quickly sealed up an old waterpump on my 22yr old chevy. that it lasted 8mo.s was impressive, but the other night the water pump again began leaking. i immediately ordered this on amazon and a day later put half the 16oz bottle in, and it immediately sealed up the same waterpump. given this waterpump is super old, i don't know how long it will hold this time, but i'm already impressed by this stuff. and i still have 8oz of it left. NOTE!!!...be warned that you need to really shake this stuff up per the directions, prior to using.