Sell materials for ultraviolet leak detection. Your pour about an ouce of a fluorescent tracer dye into the crankcase through the oil filter cap. Let the engine run for fifteen minutes or take the car for a drive. You need to allow sufficient time for the dye to mix thoroughly with the oil and to start leaking out. Then stop the engine and look underneath with your ultaviolet light. Modern 120-15W ultaviolet spotlights can be used in a lighted garage. The leak will leap out at you in bright yellow. (If you don't see it immediately wait a while. It'll show up eventually.) Wear UV Blocking safety classes. The detection principle is the same for transmission fluid and for coolant. Dyes are made that are compatible with fuel and automatic transmission fluid too, only the colors are different for each. Happily, the dyes do no harm and may be left in until you next change the lubricant or coolant. When you wahs off the outside of the dirty engine or transmission, the dye will wash off, too.

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