Tracer’s Dye-Lite TP-3100 fluorescent dye is formulated to pinpoint leaking engine oil, hydraulic fluid, lubrication fluid, compressor oil and gearbox oil. Add a small amount of the dye to the system and allow it to circulate for several minutes; wherever there is a leak, the dye escapes with the oil and accumulates at the site. Scan the system with an ultraviolet or blue light lamp, and the dye glows a bright yellow color to reveal the location of all leaks. The dye can remain in the system until the oil is changed.