I have a 2005 Saab 9-3 Linear 2.0 turbo. I was recently told that an oil change costs over $120 w/ a 15K OCI, the manual requires Mobil 1 0w-40 oil. Is there anything else that is compatible that might be available in a 5qt jug at wal-mart? $8/qt is the going rate around here for Mobil 1 0w-40, with 6 qts required, its pricy! Any suggestions?