Despite also owning an Alfa, therefore knowing how important it is to
check oil regularly, I still managed to cause terminal damage to a 3.0
V6.

I'm still not sure exactly what went wrong, but it would appear that a
faulty sump gasket caused oil loss.  The oil pressure sensor
registered positive pressure so didn't cause the oil light to
illuminate on the dashboard.  At the same time there wasn't enough oil
left in the sump to lubricate the down-below bits.

Result from the garage:
"Carried out further checks and found that piston small ends rattling
along with crank bearings noisy.  Reassemble and rebuild as required.
(vehicle requires replacement engine)"

All out of warranty.  £7,000 for a new engine, apparently.  Am I
unlucky or what?!  Or is there a design fault in the oil pressure
sensor?