TSI Supercool Synthetic U/V Leak Detection Dye, 1 oz, 1 Application

Was skeptical at first but used it and it makes it so much easier to find a leak and most of the time you dont even need the flashlight to spot it. Color is nice and bright to see definitely worth the money id buy again. Worked great for us even though the radiator is shot.

This stuff was AWESOME ! I didn't even have to use a UV light. My leak was clearly visible in the direct sunlight. I'm very impressed with this product.

Glows very bright

Works great. I would rather not use it because is is colorful enough even without UV that I think of it as messy, and drain and flush after finding and fixing leaks, but maybe I add too much, or maybe I should just not worry about that and rinse everything when done. It is quite water soluble and rinses clean off. My son calls it "predator blood", looks the same. Definitely helps finding obscure leaks on messy engines. Be sure to put it in the radiator. If put into an overflow tank, especially a non pressurized type, it may require a few heat cycles to transfer enough to where it matters to be useful. Obviously, won't help with a head gasket leak to the combustion chamber, unless you look with a borescope, maybe after letting it sit pressurized a while. Head gasket leak to crankcase (oil contamination), you shouldn't need this stuff for. The milkshake is perfectly fine for that.

Dumped into my radiator to find a small leak in my Jeep. I could smell the burning fluid, but could not find a leak and didn't have any drips in my driveway. I gave this product two days of driving around and then I grabbed a UV light and almost instantly found the leak. A small leak near the thermostat was dropping coolant on the belt and slinging it all over the front of the motor. I was able to fix the leak quickly and rinse the extra coolant and dye off the motor. I checked again the next evening and no new leaks. Great product that saved me weeks of looking for a leak.

This really shows you where your leaks are coming from. You just need to make sure you have a good blacklight source and you should not have any difficulty seeing what you need to. Don't try to do this in the direct sunlight it makes it too difficult to see.

Helped me locate a cooling system leak that I could not find otherwise. Was afraid I had a head gasket issue as I never saw dripping antifreeze anywhere. Found leak on thermostat housing that was getting flashed off on the manifold.

Definitely does the job, you'll see your leaks or at least a boatload of color everywhere there's antifreeze when you hit it with UV.

Sooooo very concentrated and BRIGHT. This product helped me diagnose a gremlin in my coolant system. 5/5 stars, great product.

The only Radiator specific dye that i could find. All others are for oil and are not compatible with coolant. It works amazing and it glows really bright fluorescent yellow under 365nm uv light form a cheap torch. The ammpount was more than enough for a very large LR4 V8 with dual AC system.

Works really well, even without a black light you can clearly see the leaks, recommend.

Good quality dye, not much more to say. Got it to find a leak in my cooling system and found 4! So yeah, works as advertised.

Worked very well. Makes it very easy to track where coolant is leaking to with a UV light. Lights up very bright when UV Light is shown on it