Oil in coolant tank, multiple misfires and coolant pressure

[no1pony]

Last night my daughters boyfriend purchased a 2003 S80 T6 with the 2.9l from a local auto auction. The car is very clean with a one owner car fax. Here is the issue:

Coolant level warning was on as was check engine light.
Codes are P0300,301,303,304,305,306.
The coolant hose seemed to be way to pressurized.
There is an oily residue in the coolant tank.
There is NO smoke at all from the tailpipe.

I am not a mechanic but I have rebuilt and repaired engines most of my life. I would analyze this to be a head gasket leak but I have never worked on one of these particular make of car. I have searched the forum but can not seem to find someone who had all of these issues.

So to those who know these engines does it seemthat there is a break in the head gasket at one of the coolant passages or am I reading this wrong.

Thanks for any help you can give.

[no1pony]

Sorry I meant to mention it has 129K on the car