I bought a new transmission pan for my 98 Expedition 4R100. Stopped the pan bolt leaks, but the drain bolt leaks. I tightened to 18 ft/lbs, but it leaks between the pan and the rubber gasket. What is the torque spec for this bolt? I am assuming this is the sealing washer and not just some sort of packing or shipping washer that needs to be removed. I have not seen one like this before, usually an o-ring type or hard plastic type.