The sediment trap (drip leg) that is connected to my natural gas pipe going into the furnace leaks oil once in a while. I tested for gas leaks with my leak detector and there are none nor do I smell any gas. Once in a while there is a wet oily spot on the concrete floor under the sediment trap. When this happens if I run my finger under the bottom cap of the sediment trap there is a clear oil on the bottom of the cap.
This is a mystery does anyone have any clue as to why this is happening?