According to Kenworth… hype has value: (surprised at this website statements)
https://www.papekenworth.com/blog/diesel-1-vs-diesel-2-is-premium-worth-it
I am really surprised at them pushing #1 so heavily for normal usage. Without a serious additive package, as a much lighter distallate #1 has far less lubricity than even #2 ULSD and modern HPCR diesel fuel systems are extremely sensitive to reduced lubricity. That is one of the advantages of soy blend diesel which restores much of the lubricity found in pre-ULSD #2 even before any additional additives. BTU content is lower in the lighter distillates with "bunker" grade (used for large marine and stationary diesels, generally requires pre-heat prior to the injection system) has the highest BTU content by volume with #1 at the lowest BTU by volume.
#1 diesel was traditionally a winter and special use fuel and as refined it generally has a lower BTU content by volume since it is a much lighter distillate. The recently marketed "premium" diesel from firms like Cenex and Exxon are a traditional #2 with an additive package that increases cetane, increases lubricity, and has a better demulsifier package to allow the fuel/water separator to achieve better separation because water in fuel is far more damaging to HPCR systems.
Unless venturing to ND in the winter (which I have no plans to do), I will be staying with regular properly treated #2.
The diesel fuel industry council needs to get it together on terminology because pretty soon "premium" diesel could mean anything from traditional #1 to #4 "bunker grade" with a better additive package.
Rodger