2007 and 2008 model years were especially bad. When GM filed bankruptcy they changed a lot of things. This is the "NEW" GM now so don't expect them do do anything about anything prior to 2010 especially. My 2009 Cadillac CTS used about a quart of oil every 700 miles. This was within their "acceptable oil usage". And there are a number of problems with the 2008-2009 CTS cars such as poorly engineered AWD driveshaft and a timing chain that doesn't last much more than about 30,000 miles in MANY of the vehicles. GM had a special agreement on the 2008-2009 with the feds about the timing chain where they replaced it with a better quality chain up to 100,000 miles and 10 years. There are many of those cars still out there that are now no longer covered that will have that $2000 job needing to be done. GM has seemingly greatly increased their quality in many areas since the bankruptcy. Good luck in your journey but don't be surprised to reach a dead end. The AFM problem in these engines is well known but GM to my knowledge doesn't even acknowledge there was an issue.
If you remember, redheadedrod, I also had a 2006 Cadillac CTS a while back.
We bought ours with 35K miles and it used oil at an alarming rate since the beginning.
As we later discovered, a poorly designed PCV system was mostly to blame for the oil consumption and many owners had resorted to installing oil catch cans to help keep that oil out of the intakes.
Our CTS engine got it's timing chains replaced at around 80K.
At just over 100K miles, the carbon buildup on the upstream side of the intake valves, caused by the heavy consumption of oil into the intake and the design of the GDI engines in general, caused a burned intake valve.
At that time, I had both heads removed and repaired.
Shortly afterwards, we traded that car off.
Having not completely learned my lesson, we traded the 2006 CTS for a 2012 GMC Acadia.
We have since learned that the timing chain issue with those engines is still an issue at least up through the 2012 model year that we bought.
Knocking on wood, so far the timing chains have not shown any problems with our GMC, but I change the oil, as recommended by many owners, at a much accelerated rate.
This engine does not seem to have quite the appetite for engine oil that the CTS did.
But, I used my bore scope to examine the upstream side of all of the intake valves when I had the intake plenum off to change the spark plugs and every one of them showed a lot of carbon build up on the intake valves.
I rarely have to add any oil between oil changes now.
However, these engines are prone to random misfires, which I attribute to the carbon build up in the upstream side of the intake valves.
That appears to be a common problem with GDI (Gas Direct Injection) engines of many brands.
Upper intake cleanings seem to be recommended by many owners and I am sure professional cleanings may be more effective than DIY solutions.
We currently have 150K on the GMC, but I honestly do not see me being able to avoid some expensive repairs on this engine if we decide to try to keep it for a while.
The shame of it is a lot of modern vehicles use GDI technology, so it is likely that we would be trading for the same situation if we moved on to something else.