Oil quick drain gasket

Morning!
Cant seem to find my answere so Ill just ask. I bough a SAF-AIR oil quick drain. I feel I must install a crush washer to seal against the oil sump.Correct?? I look on their site and the "replacement" oring/crush washer list does not list a crush washer for the P5000 but does list two of the MS28775-011 and one of the MS28775-012. Not sure why a rubber oring would be used instead of a crush washer but....
SOme of their other quick drains are pictured with a crushwasher and others Mine) are pictured with nothing. Could it be because the oil drain valve is a real light weight aluminum construction and a crush washer is too much??
Thanks for any comments
Bill

I think all the lycomings have pipe threads in the sump. No gaskets.

Bill,

The Safe-Air P5000 quick drain has pipe threads, not straight threads. There is no crush washer or any other gasket between the drain plug and the oil pan. Use a pipe thread sealant. The o-rings listed as replacement parts are the internal seals for the P5000.

Some of the other Safe-Air drain valves do use crush washers, because they thread in to straight thread holes.

That would make alot of sense. Thanks Steve!

bill