I'm thinking about getting a new leftover 2013 Ram 3500 DRW 6.7 but I was reading on the TDR about some of the trucks having short oil change intervals. One poster had to change oil 4 times in 10,000 ...
You might try going over to the Cumminsforum for better information. I haven't heard of any 2013 DEF engines with fuel dilution. Actually the Ram ad's suggest they will go 15k miles between oil changes.