I own a 2006 CTS, 6cyl, 56,000 miles. On a recent trip, after 10 hours of driving, we had to put in three quarts of oil to make to the nearest dealer. Prior to the trip, our local dealer checked over the vehicle and changed the oil. At the second dealer, they could not explain the oil consumption or the fact that both catalytic convertors had to be replaced. The third dealership kept testing the oil every 1,000 miles and kept telling us that everything was o.k. Still no explanation on the original disappearance of three quarts of oil and replacement of both caty convertors. Any suggestions as to the cause? I presently have to put in a quart of oil every two fill-ups. No oil leakage on the garage floor.

 

Rob,
How come no one responded to you. I have the same problem.

 

I was looking at a CTS,,,,googled CTS issues and found several issues with being down on oil and destroying the engine without knowing where the oil went.

A lil hesitant now,,,,glad you guys noticed the low oil.

Cant believe there is not low oil light on these

 

I have the same issue with losing oil on 2006 CTS, 3.6L. No problems until it hit 55,000 miles. It used 2 quarts in a 630 mile trip. Now I have to add a quart about every other tank. It is definitely not leaking. Also, I don't see evidence of burning it in the exhaust. It must be burning it.