I also found Mobil 1 15W-50 Extended Performance. Would that one be ok or not? I only ask as the Royal Purple is already emptied off the shelves. When I got home I was pissed as I had 4 bottled of RP....only 3 of them where 15w40 and the last was 10w40


edit: ST2 takes 3.4L oil
edit 2: yes, I read the owner's manual and it lists a buncha grades for different climates.