ACDelcoGM Original Equipment 10-5057 Engine Cooling System Tracer Dye - 1 oz

Had a coolant leak I couldn't find at all. Put this in the coolant reservoir and drove the truck for a couple hours and found the leak glowing coming from under the water pump. Good stuff

You'll easily be able to find the leak with this.

THIS STUFF literally GLOWS in the DARK-if you have a LEAK you will find it- even in the engine oil.

Found multiple leaks in the coolant system including a devastating leak in the radiator. Working to replace things now to get the car back on the road! Budget friendly; you don’t need the whole bottle. I used about a 1/4 of it.

Immediately found the leak in my system. Only thing I dislike is the instructions say to use the whole bottle. This stuff is potent. Only use the whole bottle if your doing a 5 liter engine. You should use a quarter or half on a small compact car. Weirdly, it goes in red and is meant for dexcool. But after it's mixed in the whole system turns iridescent green.

I've had a coolant smell coming from the front of my Jeep since I bought it 3 years ago and I couldn't find the leak to save my life. I've only added a quart of coolant the entire time, so I knew it wasn't that bad and I watch the level like a hawk. I decided to try this stuff just for fun and wow! I found it in daylight as soon as the engine warmed up without a uv light! It was the last place I would have guessed because the seal on the radiator cap looked fine. Once the system pressurized, it pushed past the seal and turned into steam. So THAT'S why I never saw any leaks! I was ready to replace the radiator, but all it needed was a $10 radiator cap! BUT WHATEVER YOU DO, DON'T SPILL IT! This stuff is SUPER concentrated! I spilled the smallest amount while pouring it in and tried to wash it off with the hose. Now my driveway looks like a nuclear waste spill. This is all from spilling about 1/4 ounce. And no, it's not coolant on the ground. Highly recommended!

I was losing a small amount (3 or 4 ounces per week) of antifreeze from my 2004 Toyota Camry after servicing the cooling system and replacing the radiator hoses. I could not see a leak, so I replaced the radiator cap, added stop leak and hoped that it wasn't a head gasket. I was thinking of adding a bottle of stuff to seal the head gasket when I ran across this product. I purchased this product along with a black light flashlight for about $15.00 and added half the bottle to the radiator. It then became apparent in short order that I had not tightened the lower end of the lower radiator hose sufficiently. The dye showed that antifreeze was leaking onto the splash guard and evaporating before it leaked on the ground. The dye easily rinses off with a hose so any new leaks will be readily apparent. If I were doing it again, I would start with the dye but only use about 1/4 of the bottle.

Took about a minute to detect leak with uv light, highly recommend!