Holy Crud! I've really started reading on this stuff and it really wakes me up! I'll post 2 articules I found. I found them intersting as can be!
Simplicity and Compatibility
While CJ-4 oils are being developed specifically to be compatible with exhaust aftertreatment devices, they will also provide better soot-handling capabilities and oxidation control. In short, they’ll offer increased overall performance and better protection for the new engines – and will protect older vehicles, too. Lubrizol has devised a CJ-4 product offering that provides this additional performance while maintaining operational simplicity and flexibility without the need to manage additional new components.
Considering the potential change in the market and the profile of these products, having this flexibility in operations and logistics during this transition is a welcome piece of good news. Extensive testing by Lubrizol has demonstrated that API CJ-4 is backward compatible, which means API CJ-4 oils can be used in older-model vehicles as long as the oil analysis is closely monitored and the appropriate maintenance schedule is maintained based on lubricant quality.
It’s important to resist any temptation to use anything but CJ-4 oil in an EPA 2007-compliant engine, because the higher levels of sulfur, ash and phosphorus in CI-4 PLUS oils may cause problems with the exhaust aftertreatment devices. Using a CI-4 PLUS oil in 2007 vehicles could cause increased plugging of aftertreatment devices, which could lead to reduced fuel efficiency and higher maintenance. All currently licensable categories, including API CF-4, CG-4, CH-4, CI-4, and CI-4 PLUS are not forward compatible to API CJ-4 due to the chemical limits for ash, phosphorous and sulfur defined by API CJ-4.
It is essential to follow the manufacturer’s recommendations and select an oil designed to meet your engines requirements, delivering protection and proven performance. Otherwise, warranties could be affected. Truck owner/operators will need to check with their OEMs for specifics.
The API CJ-4 requirements describe oils for use in those high-speed four-stroke cycle diesel engines designed to meet the on-highway exhaust emission standards being implemented for 2007 model year as well as for previous model years. These oils are compounded for use in all applications with diesel fuels ranging in sulfur content up to 500 ppm (0. 05% by weight). However, the use of these oils with greater than 15 ppm (0. 0015% by weight) sulfur fuel may impact aftertreatment system durability and/or oil drain interval.
These oils are especially effective to sustain emission control system durability, where, particulate filters and other advanced aftertreatment systems are used. Optimum protection is provided for control of catalyst poisoning, particulate filter blocking, engine wear, piston deposits, low and high temperature stability, soot handling properties, oxidative thickening, foaming, and viscosity loss due to shear.
Engine oils that meet the API Service Category CJ-4 designation have been tested in accordance with the ACC Code of Practice and may use the API Base Oil Interchangeability Guidelines and the API Guidelines for SAE Viscosity Grade Engine Testing.
API CJ-4 oils exceed the performance criteria of API CI-4, CI-4 PLUS, CH-4, CG-4 and CF-4 and can effectively lubricate engines calling for those API Service Categories. When using CJ-4 oil with higher than 15 ppm sulfur fuel, consult the engine manufacturer for service interval.
The first license date for API CJ-4 will be October 15, 2006.
Effective May 1, 2006, marketers may license products meeting API CJ-4 requirements as API CI-4, CI-4 PLUS, CH-4, CG-4 and CF-4.
Oils in the API CJ-4 category evolved from the heavy duty diesel specification known as Proposed Category 10 (PC-10). These oils are formulated to enable the use of increased EGR rates and new exhaust aftertreatment devices in model 2007 on-road diesel trucks to help meet the 2007 EPA exhaust emission standards. To be compatible with exhaust aftertreatment technology, CJ-4 oil must meet chemical restrictions of less than:
1. 0 percent ash;
0. 4 percent sulfur;
0. 12 percent phosphorus.
CJ-4 oils also offer a number of performance benefits over previous API categories, including:
High-temperature antioxidancy;
Enhanced soot control;
Enhanced low-temperature pumpability;
Lower levels of oil consumption.
CJ-4 oil is formulated to be compatible with exhaust aftertreatment systems required for on-road model year 2007 diesel trucks.
After reading this, I'm thinking that DC is behind on this and CJ-4 should be used. I got the requirements right off the DC computer for what is required on the new 6. 7, and it says CI-4 LOL
Attention: TDR Forum Junkies 
