Engine oil in throttle body

I am looking for information on why there is engine oil in the throttle of my 1997 impreza wrx sti.. We took the engine out to see a lot of oil has leaked around the engine and some oil in the throttle.. Has anyone had this problem before and if so waht was the diagnosis..

If your running the standard breather system. I.e recirculating it into the engine via the inlet pipe after afm and before turbo.. This is most likely the cause...