TSI Supercool RD8 Radiator U/V Leak Detection Dye, Purple 8 oz — Water-Based, Self-Measure Bottle

TSI Supercool RD8 is an 8-ounce, water-based purple U/V radiator dye in a self-measure bottle designed to reveal cooling-system leaks quickly under any U/V light.

This concentrated synthetic dye mixes with coolant or water to make leaks visible when inspected with a U/V lamp. The purple formula is water compatible and formulated for rapid fluorescence, giving technicians and DIYers a fast way to locate leaks in water-cooled engines without dismantling the system. The bottle’s built-in measurement markings simplify dosing — one ounce treats a single vehicle — and the dye is formulated to work with common coolant systems.

How do I use the RD8 dye to find a leak?

Add the measured dye to the radiator or coolant reservoir while the engine is cool, run the engine briefly to circulate, then inspect with a U/V light. Any breach in hoses, gaskets, or components will fluoresce purple green under UV, revealing the leak source for repair planning. Follow vehicle and product safety guidelines when topping off fluids.

• Use 1 ounce per vehicle as directed on the bottle.
• Pour into the radiator or overflow reservoir with engine cold.
• Run engine to circulate, then scan with a U/V lamp in a dim area.
• Look for bright fluorescence at hose joins, seals, or around the water pump.

Will RD8 work with my car’s coolant?

RD8 is water-based and designed to mix into most conventional coolant and water systems used in water-cooled engines. It is intended for diagnostic use and dyes the circulating fluid so leaks become visible under ultraviolet light. For application in unusual or manufacturer-specific systems, consult the vehicle manual or a technician before use.

• Compatible with standard antifreeze/coolant and water-cooled systems.
• Designed for diagnostic tracing, not as a long-term coolant additive.
• Safe for typical cooling components when used as directed.

How soon will I see the leak after adding the dye?

Fluorescence is usually visible shortly after circulation; small or slow leaks may take longer or require a pressure check to force dye through the defect. Inspecting with a U/V lamp in low light improves contrast and helps spot faint traces. If no dye shows, repeat the check after additional run-time or perform a pressure test to confirm.

• Most visible after a few minutes of circulation.
• Use a U/V light and dark environment for best results.
• Pressure testing can help reveal slow leaks that don’t show immediately.

Who this product is for: TSI Supercool RD8 suits automotive technicians, fleet maintenance teams, and DIY vehicle owners who need a reliable diagnostic dye to pinpoint coolant leaks quickly. It’s especially useful for troubleshooting intermittent or hard-to-find leaks without extensive disassembly. The self-measure bottle and single-ounce dosing make it convenient for occasional use or for keeping in a toolbox for emergency diagnostics.