I know a guy who had his Dmax run-away on oil when he blew his turbo at the track not long ago in Edmonton. And really, any turbo engine that doesn't have a positive air shut-off to kill it can run away on oil. Especially compression ignition engines.
Also yes, you need boost at higher oil pressures to keep the seals from allowing oil to pass. Simon had this issue when his modifyed oil pump had too high an oil pressure. Oil used to spray out of the hood stack at idle from the atmosphere turbo!:rofl:
No turbo should have oil in the compressor housing though in normal conditions with nothing to cause it other than a seal failure. I'd start looking for aftermarket replacement turbo options if it were me.......