
Got myself a torque wrench to be safe.

First, loosening, turn of the wrench

nasty noise

put bolt down on strategically placed kitchen roll

notice strange silver residue and threads

Drain oil (both plugs)
Re-insert bottom bolt and turn to correct torque

Except, no torque, no resistance, in short, no fucking thread

Only thing I can imagine is that when it was last (1st) serviced, they must have overtightened to the point where it was stripped down to a fine grain but not far enough to drop back out again.
So, good news is, it didn't vibrate out at 140mph on the Autobahn

Bad news is, need to re-tap the hole

So, apart from generally sharing the misery, does anyone know what size bolt/thread Aprilia go with for the lower oil drain plug?