The cause of the oil coming out is indeed an increase in crankcase pressure forcing out the oil. This means that there is either excess pressure being forced into the crankcase from somewhere or the pressure is building up because it cannot escape by its normal route.
As I've got one says the first thing to check would be the breather hose simply because its the easiest to do! The hose is the one coming from the centre of the right hand end of the cam cover and connects to the intake hose. Pull it off and check that it is not blocked, check that the connectors where the pipe pushes onto are also clear. Quite often the rubber hose collapses due to the oil vapour and other gases eating away at the rubber, the outside of the hose can look brand new though so don't fooled. It should be OK though on a fairly new car.
The other more serious cause is that gases are escaping from the combustion chamber increasing the crankcase pressure dramatically. This can happen via a few routes. Around the valve stem seals or ideed as your friend says past the piston rings. A compression test should highlight a problem clyinder and narrow your investigation.
