Oil for diesels?
I personally would use the diesel rated oils. You can do more research but when I looked into this several years ago, most people indicated that oils specifically rated for diesel are the only way to go. This is what all the big trucks use, and since those companies have a lot riding on picking the correct oil, I would say that someone has done their homework for them. I'm not a chemical, or automotive engineer, but the reason for using diesel oil seems to have something to do with the particles that diesel oil gets contaiminated with. Diesel oils are formulated to handle this whereas the others are not.
I can get Shell Rotella T at Walmart for a fair price, so I go with it. I buy it when I make the normal toothpaste, laundry soap run....you know.
But, as they say, your mileage may vary.