CADILLAC STS ENGINE BURNING OIL

I Purchaced This Car Witn 18500 Mi.I Ckd Oil At 22000 Mi And Very Little Oil Was On Dipstick. Dealer Changed Oil Mobil 1. Dlr Rep Said It Is...

My Car Uses 2.5 Qts Of Oil Every 5,000 Miles. I Can Not Drive Any Further Without Adding Or Changing The Oil As The Car Will Begin...