Both US and Canadian law requires ultra-low-sulfur diesel (ULSD) in all new diesel engines made since 1/1/2007 (in the USA, anyway). By law, ULSD is all that is sold in the USA these days for on-highway use.
Is that what you were asking about?
You will get more answers to technical questions in some of the other iRV2 forums - this area is primarily to introduce yourself.
By the way, welcome to iRV2!
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL