Originally Posted by TDI-Minnie
DEF is not the only emissions "game in town".
Many have used DPF and EGRs for years. Those are diesel particulate filters and exhaust gas recirculator. I will say DEF is least harmful to the engine, but just because your diesel doesn't use DEF, doesn't mean it is not regulated to the same level. 2012 was the last year Ram used DPFs on the Cummins. Now they are all DEFs.
Best efficiency and long engine life is of course, none of this stuff!
Nothing else was able to meet 2010 emission standards. All these diesel have DPF's for particulates, DEF and EGR are not for particulates, they are for NOx emissions. Dodge/Cummins used credits to get by until 2012. Ram still has DPF's along with the DEF since they are for different emissions (soot vs NOx)
Navistar tried advanced EGR and where unable to get NOx emissions low enough. They tried using banked emissions credits past 2012 to keep selling engines without DEF and Volvo sued the EPA to get them to stop as they and everyone else had to go to DEF. It did not go well for Navistar.
The most efficient engines run lean and hot, unfortunately running very lean and very hot like a diesel also creates NOx from air which causes acid rain and respiratory problems.
As I stated EPA doesn't care how you get NOx emissions down, DEF is the only way to do so with current technology and meet 2010 standards.