Tracerline's Dye-Lite Clear-Blue fluorescent dye, No. TP-3920, is a specially formulated dye for detecting coolant leaks and is safe to use for both extended-life and conventional coolants. It is approved for use by Ford. Clear-Blue will not discolor the coolant; leaks are best diagnosed using a high-intensity, long-wave UV inspection lamp. When the system is scanned with a Tracerline inspection lamp, the dye glows a bright blue to show the exact location of leaks.