The plug in the bottom of the oil cooler leaks. I have tried a new washer from Mazda, heat treating the washer (per D.C), and PTFE pipe tape that was spec. for oil and chemicals and was good to 450 deg. . I also tried cleaning the plug and the flange and inspected for burrs, gouges, etc. (didn't find any). So i'm about ready the throw that thing in the trash! Anybody got any other suggestions? I ordered a new plug and washer from Mazda and i'm thinking of removing the oil cooler and taking to a machine shop to check the flange.

Todd

 

Take it to a radiator repair shop and have them look for cracks around the fitting. That is almost always the cause of oil leaks on the oil cooler. They would be able to weld the crack for you.