two possibles here:
1. someone put oil in the wrong 'ole.
2. headgasket gone.
I'd check oil level and top up as rqd, drain and refill coolant, go for a drive, check both oil level and rad (for oil). If both are ok it was cause 1 and all is now well. If not you need your big toolbox and a headgasket set.
Andy
May 2008