I'm sure this question has been asked a number of times, but I can't seem to find it in a search...anyway, what is the scoop on 1) SuperTech synthetics? & 2) Mobil 1 (non 15K extended) oil? In regards to #1, the Wal-Mart 5qt jug has WPP (Warren Performance Products) on the bottom. The discription on the back of the jug says made with 100% synthetic base stocks, so is the a group IV oil? This stuff use to cost about $13 a jug and is now up to $17. #2, Wal-Mart has Mobil 1 back down to $22 a 5qt jug again, but it does not say "extended performance" on the label. Is this still a group IV actual 100% synth base oil?