I have an 05' that was recently overfilled on oil by the "quick change" place by about 2.5 gallons. First it started to come out the blowby so I checked the level and corrected it. Then it got harder to start and smoked blue when cold, now it has broken rings on 5&6 with carbon down to control rings on all 6. Did the overfill kill my engine or is it all a coincidense?

 

Overfill just makes the crank hit the oil and make it foam.
Can lead to bearing failure but not rings.
You have it apart so rebore if nessesary and rebuild it!

 

Sounds like you lost an injector or two and filled the crankcase with diesel fuel and not oil. Pretty common and can be catastrophic. If you're gonna rebuild you should look real hard at all six injectors before you fire her up again and damage those pistons/cylinders again.