What is diesel fuel oil made of ?

Used oil

Diesel fuel is one of the products created from crude oil. During the refining process, the viscous dark thick crude oil is turned into the much lighter diesel fuel.
Diesel fuel is a mixture of hydrocarbons—with boiling points in the range of 150 to 380°C—which are obtained from petroleum. Petroleum crude oils are composed of hydrocarbons of three major classes: (1) paraffinic, (2) naphthenic (or cycloparaffinic), and (3) aromatic hydrocarbons. Unsaturated hydrocarbons (olefins) rarely occur in the crude.
Then what is diesel fuel made from?

Used oil to diesel fuel refinery plant

Diesel fuel oil made from all kinds of waste oil ,such as  waste tire oil ,waste plastic oil ,used motor oil ,waste engine oil ,black oil ,etc.
If we want to get clean fuel oil ,used oil to diesel fuel  is necessary to the diesel fuel oil