Engine leak dye
The Dye-Lite TP-3100 fluorescent dye helps pinpoint leaking engine oil, hydraulic fluid, lubrication fluid, compressor oil and gearbox oil. Dye added to and circulated in the system for several minutes allows leaks to be seen with an ultraviolet or blue light lamp. The dye glows a bright yellow to show leak locations. Dye can stay in system until oil is changed.