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

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.

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

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

This stuff worked great, one ounce was more than enough. For those who said the product didn’t fluoresce in the bottle, I believe it needs to mix with the coolant/water to really light up. Remember this is to be used with a black light/UV light to see the leak. While it was bright enough to see some areas with no artificial UV light, it is ideally used with a UV light. Super bright for me, showed the leak clearly and was in an area that I never would have thought of or found without the leak detector.

Very strong, only need a little bit to make all of the coolant extremely uv visible. Helped me find my leak

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.