Originally Posted by
Gonewrongmark
If it were a head gasket there would be White in oil.
That depends on where the headgasket has failed, it could be the gasket has gone between the combustion chamber and the water gallery which will pressurise the water system and show symptoms like you are experiencing, headgasket issues don't always show up as oil in the water on a Subaru, it's best to get it diagnosed by a specialist before you start spending money.