According to George :

I think you may be mixing a few terms. "Diesel oil" is a product that
varies according to climate and isn't a specific oil # grade. #1 is
kerosene by definition.

At the refinery, there's rather more than that - I had a summer job at
a refinery testing the raw feeds straight off the distillation and cracker
units. At the one I worked, they had "heavy" and "light", in diesel,
kerosene, naptha and gasoline - and there was some considerable
crossover and confusion about nomenclature (the specs are what
matter not what they call it) especially at the gasoline end.

The light and heavy kerosenes/diesels/napthas were pretty consistent
straight off the units and were mixed in relatively fixed proportions
to make each of the desired final products with their own naming
conventions (#1 diesel etc).

The light and heavy gasolines were all over the map (some lights were
so light they'd boil in your hand from skin temperature alone), and the
results of mixing had to be tightly monitored to attain the proper
properties. Then of course there's all the stuff about octane ratings...
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.