2007 Cadillac CTS

The 3.6 is a very stout engine with a good reputation. Sometimes things just happen- not every one of the hundreds of thousands of those engines will be perfect. It lasted a while, and usually a defect will show itself in the first few years. I have two cars with the 3.6 myself and love them. I'm a retired GM service manager and it was very rare to see one with problems- never seen a "blown" one at all. Usually the issues over time are external or superficial, like oil buildup on the valves because it's direct injection or catalytic converters, emissions parts, etc.