WillWagner is far more knowledgable on diesel engines than I am, but I am still going to use an additive in my old diesels until CJ-4 has been OTR for awhile. Up until a few months ago I was still able to buy CI-4, but now it is scarce as hen's teeth in my area. It may cost me a little extra dough, but I will sleep better using an additive even if it does not help. Of course if someone out there has LDT465. 12V 6BT or Caterpillar DD4400 diesel that have been run 3 - 4k hours on the CJ-4 without any wear related failures I would forget about going with an additive.