Engines produced after Jan 1, 2007 must use this low sulfur diesel. Your motor is safe to use with the new diesel. it is the 2007 manufactured engines that must use the new low sulfur fuel.
It is similiar to when the nation converted to unleaded gas in the 70's. If you ran the leaded on the newer cars it would stop up your catyltic (sp?) convertor the old fuel will damage the new engines.
I think this new fuel has been out a while. The stations are converting well in time for the 1st of Jan.
I Think there are some oil issues that is affected with the fuel change but not sure how it affects. there are some threads on the RV.net Class A forum about this and the oil gets discussed in the thread.
Hope this helps......
2006 TourMaster T-36 / Good Sams / FMCA 380624