Review on 🔍 Spectronics Corp/Tracer TP39000601 1oz Engine Coolant Dye - Set of 6 by Bill Martinson

One bottle is enough for most car engines. The engine coolant glows bright yellow (opaque) when using a UV flash. I have a 365nm LED that I bought for about $33. The best time to find a leak is when it's pitch dark outside. My problem was that the coolant leaked out very slowly over 2 weeks and only when the engine coolant was at or above operating temp (probably when the thermostat opened). .I was able to find the leak very accurately and quickly. I also have 5 bottles left.