The 2003-2007 5.9L Cummins seemed to have injector issues and sometime after 2008 Chrysler updated the filtering system on the 6.7L diesels. Before that the VP44 trucks were good on Low Sulfur Diesel but not Ultra Low Sulfur Diesel and many many VP44s broke (either from the ULSD, faulty lift pump or from a combination of both). I used to run two cycle oil in my 2001 so the VP44 was for sure lubricated and I used up the rest I had in my 2008 but now I run nothing. The fuel suppliers have wisen'd up and started adding lubrication to ULSD but I don't know when they started doing that. So no worries about lubrication. If you REALLY want, you can do a cost analysis on additive and see if even doubling the life of your CP3 is cost effective even if adding something to your fuel would double the life expectancy
(which I doubt highly). Better money is spent on filtering your fuel and oil if you really want life expectancy out of your injectors and CP3 injection pump and the engine in general. Yes, filtering costs, but not as much as the alternative.