Exxon Valdez in My Garage

[Grumpy Goat]

...
All of this still boggles me.  There is nothing I found that the crush washer shouldn't seal around.  We're not sending people to the moon here.  Just trying to keep fluid from leaking out of a hole.  This is definitely not brain surgery.  But, then again, I'm an American engineer, not a German one.  My idea of precision for a specific application may differ.

Agreed 100%. This Canadian engineer would have had far less patience and tolerance than you, given the level of "swiss-watch refinement" of these powertrains. Thankfully my RS has not presented such a challenge to me yet.

Speaking of plugs ... I replaced the drain plugs in both my engine and FD with Dimple magnetic plugs some time ago (not sure if they are still in business since the URL does not work) and have no similar issues before or since. If changing the oil drain plug you might want to consider similar. A stronger magnet won't hurt.