The Tracer Products Fluoro-Lite 5 UV Dye is an improved fluorescent dye formula that is up to 10 percent brighter than previous formulas, the company says, and offers a shelf life of up to five years. Other notable features include increased resistance to extreme temperature ranges of moisture; co-solvent free to maintain viscosity and lubricity; and is made of natural, safe raw materials. This dye is designed to protect vehicles long-term once in the system, so users can tell if other leaks show up.