Got in touch with Cadillac.com. My engine light is on and I took it to an auto parts store and it read "cam shaft ' and differential problem} I told the rep that I thought 54,000 miles was a little early to be having motor problems. He said I didn't know it was really a problem with the motor - take it to the dealer - and have them run the diagnostics, so we could see what was really going on. I griped about taking it to the dealer and paying THEM to tell me what was wrong, so he agreed to pick up the 95 dollar diagnostic tab. SOOOO, you all know what happened! the mechanic ran the diagnostics, which he said would take 1.5 to 2 hrs to complete (so they dropped me off at home) and he told me he'd call me and tell me what was up - no charge- and tell me about what it would cost to fix. Again, you all know what happened. He called me and said it could be the cam needed a shaft, it could be the cylinder had to be replace, hell they weren't sure what could be going on until they took the top of the motor off, and the cost would be 400+ best case or 2200+ worse case, but don't quote me on that because the timing might need replacing, so it could be much more even. REALLY?????? And what's it REALLY gonna cost to take my engine apart, and what are my choices after the engine's apart, and OF COURSE, it's the thousands of dollars in repairs that need fixing, and "oh, by the way, if you want it back the way we found it, we've been working on it already for hours and ........ REALLY ? No, I'll pick it up, and it can sit in the driveway. I'll be back on the phone with the Cadillac customer service guy. I'll let you know what they say.....

Update from Aug 27, 2013: customer service called back (took a week). They are contacting the dealer to find out how much it will cost me to take the engine apart to find out what's REALLY wrong and how much it will REALLY cost, and if I elect not to spend thousands on this 54000 mile engine fix, how much will it REALLY cost for them to put it back the way it was and let me take it home......supposed to call back today (Tuesday, 8/27) after they speak to the dealer......PS It was not 'cam needed a shaft, as I wrote. It was the cam shaft may need a shim.......