I have a bit of experience with heli coils...like he stated above, over tightening and stripping the softer aluminum is a real possibility, so throw that torque wrench in the trash before you even think about using it again for the drain plug or filler.
Perhaps this is because of the material it is threaded into. The rear drive is a cast aluminum piece. Is the oil pan cast or formed (I assume cast)? Either way, it is likely to be a different alloy and may exhibit less tendency to strip. In any case, I don't use a torque wrench for either and I am pretty sure that I tighten the oil drain lug to a lower torque than specified in the FSM. I haven't ruined one yet (or had a leak).
I know many here advocate for not having to change out the crush washer each time and I agree it probably isn't necessary to prevent leaking. Doing so though does give you a good indication of how tight you need to go. Once you feel the 'crush' of the new washer you're probably good to go. (Or stop as the case may be.)
What's neat about the solid washer (with the outboard), it tightens down much faster without the "is the crush washer crushing or am I stripping the threads" feeling.
I was trying to torque to 17 ft-lb. I believe the ***** that stripped it out was me the last time I changed the oil. I blame my inexpensive Harbor Freight torque wrench. I remember last time I changed the oil that I had tightened past the "click". The click is so subtle on those wrenches and at only 17lbs I didn't notice it. I can't tell you how far past 17lbs I went, but it couldn't have been too much. I'm with HotRod. I've been changing oil for 30 years without a torque wrench and never had a problem. From now on, tighten until snug and call it good.
And more importantly, inch lb or ft lb and if so, the actual range.
