I posted the original question last year, thought I had a heater core problem. The problem was actually a leaking evaporator and I was seeing the dye/oil leaking through the discharge hoses by the tranny. Replacing the evaporator is a major time consuming job a tres expensive. Instead, I discovered a product called Cryo-Seal made by SSR Int'l and had it installed by an independent. About $195 for materials and tech time to flush and replace some other components and add freon. About 18 months later, air works fine and no signs of visible leaks. Steve