I'm also having this problem. Been adding 1qt every 1000-1500 miles. Using Mobil1 5/30. I first noticed the problem started back when I had 58K miles. The engine is dry, no visible leaks.

Has anyone identified the root cause yet? I performed a search, but nothing conclusive
Thanks

04 Bonneville SSEi

its got to be going somewhere, possible hard to find areas include the oil pressure sensor(happened to me), anything on the back or valve cover gaskets will drip on the manifolds and burn off

^^X2

I rarely hear of 3800 engine consuming oil internally unless they were badly abused. I would definely check valve cover gaskets. My valve cover gasket was leaking so bad, I was losing a quart every 1500 miles. However my car did smell like burger king after every long drive .

this happened to me. every oil change i was down over 2 quarts. my LIM gaskets were leaking slightly, my valve cover gaskets, and a few other things. oh oil pan gasket also. had them all replaced and no more oil consumption. my car also smelled of oil when my heat was on and idling for a while. hope this helps