Can't remember where I read it, but the article said that starting 2006 the Cadillac Northstar engine was redesigned to be better than it's predecessor. It this true, or not? I have been toying with the notion of a 2009 DTS with 66,000 miles on it.
Should not have a problem at all with it. I think around '06 they updated the head bolts so they are stronger, longer, and have more threads for more bite. Make sure the car has all the service history on it. Along with no rust, and been garaged. Check the cooling system, ask questions about the cooling system, if its been flushed and the appropriate brand name coolant from GM was used. Other than that it sounds like a real good vehicle! Oh.....and ask "show me the carfax" it'll give you a good base to start. Others will chime in shortly.
The change to the head bolts actually happened in happened midway through 2004, so the 2005-2011 DTS doesn't suffer the same random headgasket issues as the previous generations. Its still an aluminum engine, though, so if it was overheated a lot for whatever reason, the block is still going to want to warp. The engine wasn't redesigned, though.
