Genuine GM Fluid 12378255 Cooling System Seal Tablet - 4 Grams, (Pack of 5)

These pellets are the best thing for a small leak. Not going to fix a water pump or head gasket. Just take a hammer and crush them in the package and pour the powder in the radiator while running. put the cap on and drive it for about 10 miles and park it.

I was told to use these with a fresh engine build and new cooling system on my Tahoe.Seemed to work good enough, I never had even a hit of a coolant leak or smell under the hood.Fast forward a few years, I pick up a jeep wrangler that needed the engine rebuilt.With the fresh engine, I also freshened the cooling system.I kept noticing a faint coolant smell under the hood, but no drips.Then I remembered I had half a pack of these things left from my Tahoe build sitting in my toolbox.I dropped in two tablets per the rough estimate of the cooling system capacity, and after one good drive the coolant smell is gone!I understand these are a one-time use thing, don't use them again unless you replace components along with the coolant, so it's not an add every week type of a thing.

Dropped the directed tabs in according to radiator capacity. Leak stopped.

I guess they work. Had already fixed a leak im the heater core of 1994 caprice with k-seal because I didn't find out about these until later. But when I changed my water pump I had to drain my coolant and used these on refilling.No leaks still.

What I did was crush 1/3 recommend amount into powder then pour into radiator and go for a drive for an hour it helped. So I added a little more crushed and repeated the next day my heater core has stopped leaking.In machine shops during the assembly of engines we used to place these exact genuine GM tablets behind brand new freeze plugs. GM service manuals recommend them in applications. They have worked for decades and they are a great choice they don't sludge up cooling systems if used correctly.

seams to hold

I found on a forum that all GM vehicles from 1999 year to 2008 years need this added to the coolant if I remember right. I've never seen this or heard of this. I had just finished a full rebuild and after replacing all cooling system parts I drop could smell coolant after driving. I pressure washed a few times now in the engines bay, but the smell kept coming back. I would smell it when walking around the front of the vehicle.Meaning there's a leak somewhere still. I added these as there's a tsb stating to add them. A week later, no more smell!!! I'm very happy with the results! I put this in all my GM vehicles. 2004 Cadillac, 2000 Silverado, 2002 avalanche. It works!

This product works. It is a natural product and I highly suggest the use of this item. Use as described In the directions. One package can be used on a full sized SUV with a 17.5 quart capacity V8. Flush sytem prior to use. I suggest crushing and mixing into a container with water to make it easier to put in. Run your car like you do normal. So the product can get into all them small places you might be having a small leak at. Highly suggest this to anyone who might be scratching their head trying to figure out wear they are losing coolant from. Use as directed on package do not exceed because you could possibly clog up your cooling system. That is the reason I suggest crushing the tablets mixing into water to achieve what your looking for. No leaks.

does not work. it actually made my leak worse. it was just a little leak and now i have to replace to rad. in case anyone is going to ask. yes i placed them in both the rad and the reservoir tank.