its Mobil 1 0-30.
I just visited my local Porsche dealer, one of the largest in the Northeast and the service manager said that all Porsches get Mobil 0-30. He said that's the only grade that Porsche will send them. So if it was good enough for that Carrera GT its the right choice for my BoxsterS.
I'm going to see fi I can buy my own oil and take it to a ASE certified oil change place. THe dealer charges about 6x what the Mobil 1 station charges. I also picked up a filter & filter wrench.
This place has the 0-30 for under $10 a bottle.
http://www.autobarn.net/rodi/mo1raoil.html