TSI Supercool RD8 Radiator Coolant Water Based U/V Leak Detection Dye (Self Measure Bottle), Purple, 8-Ounce Bottle

This stuff is very concentrated. Just a small amount is enough to dye an entire cooling system. It helped me find a small leak that would have been very difficult to see otherwise. Super easy to use - just dump it in and let it cycle. Be careful not to spill or splash though.

Nice and bright fluid really helped me find my leaks. It really helped me pinpoint my coolant leak, sadly that leak was from the intake manifold instead of something easy.

It worked great, you almost don't need a light to find this. If you have a large leak it will look like a Scene from alien.

Great product

This works absolutely perfect, I put the whole bottle and probably shouldn't have because my coolant was super neon green but I sure did find my leak with this I definitely recommend

Everything arrived as advertised. I haven't used it yet but looks to be perfect! I will post pictures after I use it.

I mean it works. Can't ask for anything more. Used it to find a coolant leak after replacing radiator and hoses. I was still leaking coolant after getting it replaced at a shop and I decided to take it into my own hands to figure out where the leak is coming from. Turns out they didn't tighten the hoses!! Probably saved me from them scamming me out of more money.

Works well, but I'd use way less than is recommended. This stuff is crazy concentrated and messy.Only downside is once it's in there, it's a bear to get out. It'd take a ton of flushing to get it all out.