I understand that the 06' s and older trucks can run both, and the 07+ Trucks can only run ULSD. What happens to an 07+ is you run #1 or #2? I'm glad that I got my truck when I did so that I don't have to find this new ULSD

I don't think it will hurt the engine other than maybe filling up the particulate trap sooner. The big reason is the 2007 emission laws pretaining to diesels.

MikeyB

Mikey is right but my understanding is a clogged trap will end up costing you $1500 and there is no way to bypass it.