I developed an oil leak at the drain plug on the oil tank of my 2003 Sportsman 400.It was time to change the oil so I did and used the same plastic sealing washer cause it was very smooth and did not have any issues.It still leaked around the plug so I drained the oil again and put on one of the metal crush sealing washers but it still leaked at the plug.Drained oil again and put teflon tape on the oil plug threads and went back with the original sealing washer and torqued to 14 ft lbs.It still leaks about a minute after I put a little oil in the tank.The surface on the oil tank is smooth where the sealing washer goes and I can’t see any crack in the tank.Has anyone else come across this problem? I do not have a new plastic sealing washer but I have the metal crush ones.Any ideas or help would be appreciated.Thanks guys,Bill.