My 2005 CTS is using 2.5 qts. of oil in less than 2000 miles. Is anyone else having this problem, the dealership is giving me the run around about fixing the problem. Let me know if you have or had a simlar experience and what you did to resolve it. Yes the car was sold to me as "Certified" and it is not yet out of warranty. the dealership has acknowledged that at least.