I bought a new Buick Regal CXL in July 2011. In that time, the steering rack has had to be replaced (because they'd never seen one fail like mine had.) The OnStar computer failed completely and had to be replaced (That, apparently was also an uncommon repair.) While it was in for the OnStar repair, it was discovered that the cam actuators for both intake and exhaust were bad and had to be replaced. The noise that was supposed to disappear with the replacement of the cam actuators came back yesterday (8/21). I picked the car up from the service department the day before (8/20) and drove it several times that day without problem. Now that the noise is back, I am concerned and would love to talk to someone about what I'm experiencing.