Certified A/C Pro Car Air Conditioner Leak Detector Dye, Leak Detection UV Dye for Cars and Radiators, 1 Oz, InterDynamics

I had my doubts, but this worked great. I was having a hard time tracking down a leak on my 2019 Ford 150. So many hoses! This turns the coolant neon green. With a UV light it's incredibly easy to see.

I ordered the UV dye and a $9.00 uv flashlight from amazon to troubleshoot a very difficult leak in the cooling system of a fiero. I could see drips of fluid on the frame under the engine, but I could not find any evidence of leaking hoses nor any solid evidence that the leak was coming from the water pump. Just to be on the safe side, I used 2 doses of the dye in the fieros cooling system since it holds about twice as much coolant as a regular car. I waited until dusk and examined the engine with the uv light. The dye showed up bright and clear and I was able to quickly rule out hoses and water pump as the source of the leak. The leak is in a very difficult to view area of the block and behind a heat shield, so I can't get a direct view of the precise place it is leaking, but the drips of dye leave marks even after the fluid dries out so by process of elimination it appears that I have a leak from the head gasket. If I had better access I have no doubt I could see exactly where the leak is, but that would require some disassembly and possibly putting the car on a rack which I haven't done yet. All in all, this stuff worked great for finding a difficult leak. The leak seems to only happen during actual driving. When I stopped and let the car idle while looking for the leak I could smell but not see any evidence of the leak. (possibly drips drying on the hot block and exhaust). With the dye I could clearly see where the fluid leak had been and places where it pooled (around the oil pan lip, etc) where I never would have noticed it without the dye. I also showed the car to a mechanic during the day. The dye was visible under uv light during the day as well. I think I'd still prefer to do real troubleshooting in a light-limited environment, daylight visibility was certainly good enough to confirm findings or get a better look at the problem overall.

Works exactly as intended. Had my car out back after a delaminated crank pulley caused the belt to eat into coolant lines going to the oil cooler. Was a pain in my Audi as could not see where the leak was coming from despite my best efforts. Ran this through pressurized the system before taking the coolant system apart to find the leak in a place I wouldnt have seen otherwise. Highly recommended. I used half bottle with great visibility

One of the best dyes - glows orange with black light and UV glasses. Prices look like it dropped recently, as the local auto parts stores have dropped their prices lower than Amazon. Try and check your local auto parts stores before committing to buying from here.

Great product, helped me find a coolant leak in my car that I just couldn't find without it. I smelled the leaking coolant but couldn't see where it was coming from, as the amount of coolant lost was so small. I added half of the bottle, waited a few days, and saw nothing different. I added the rest of the bottle, and a few days later I saw the leak. I used a black light flashlight Escolite UV Flashlight Black Light, 51 LED 395 nM Ultraviolet Blacklight Detector for Dog Urine, Pet Stains and Bed Bug , and even in the garage, with the garage door open and garage lights on, the dye stood out brightly. (It was a hose that went from the top of the radiator to the overflow tank. I added a small hose clamp to fix it.) Why did I start with just half a bottle? We have 2 other cars, one is 13 years old and the other 15 years old, and I wanted to save the rest just in case I needed it for one of those cars. Other reviewers have stated that half a bottle worked for them. Maybe it would have worked for me as well if I had waited a few more days, but then again, the extra dye probably made it stand out even brighter. It was unbelievably easy to see, a bright neon color. After adding the hose clamp, I was able to wipe the dye off the radiator neck and it did disappear. Be sure to read the label - it can't be mixed with Dexcool anti freeze.

This works absolutely fantastic. I was chasing a slow coolant leak for about a month & couldn’t figure it out. I bought this & the recommended light + glasses. Found the leak after about 3 days. It glows nice & bright with the recommended light.

I poured the whole bottle to the radiator to mix with about 7 qts of coolant. No sign of external leakage even after a few days, checking with a UV flashlight. Been adding about 1/4 quart every other day to bring coolant back to normal level. Engine and transmission oil at proper levels and no sign of coolant contamination. No smell of coolant in exhaust, even shined UV to tail pipes but found nothing. Got my SUV on a ramp and try to look for leakage underneath but found nothing. Pressurized through the radiator cap to 16 psi, dropped to 14 after 5 minutes but remain there. After spending twenty bucks for the dye and UV flashlight, I still have no clue as to where the coolant disappear. Might have to send a sample of engine oil to Blackstone for analysis to see if coolant may leak to engine (must be small). Leaving 3 stars for now. Updated: It turned out I had a blown head gasket in my SUV. The leakage was small and internal so this dye did not help. However, once I removed the coolant hoses and the head, the effective of this dye is quite evident. It turns the blue Honda coolant into neon-green solution which is easy to spot even in daylight. Bumping it to 5 stars.

I bought this very skeptical, recommended by a friend. I only used half a bottle after reading all the reviews of how potent it was. I was blown away by the potency, and how fast it worked. I immediately was able to find and pin point my leak and saved me thousands of dollars.

I use it for checking leak path in automotive heat exchangers. Works good.

WORKS AS IT IS SUPPOSED TO. MAKES LEAKS VERY VISIBLE.

It's a lot cheaper to do the ac recharge my self, this it the second time I've bought this product from this seller thx very much

Needed to find a leak in my cooling system so added the bottle to about 14 liters of coolant. Chose this as it was inexpensive and available the next day. Mixed quickly and shows up very bright under UV light. No reason to spend any more money on something fancier

Right item, good price and great service