According to Richard J Kinch :
dpb writes:

Well, it's not "just" kerosene, it's a mixture with naptha-like
fractions for its penetrating ability.

CAS No. Chemical Name % Range
64742525 Naphthenic Petroleum Distillate 40 - 60
8008206 Petroleum Base Oil 40 - 60

No, you're confused. Naphthenes (cyclic hydrocarbons) are not naphtha.
Kind of like paraffins (chain hydrocarbons) are not wax. These are
confusing terms from 19th century petroleum biz, kept alive to baffle
consumers. In those days, they distilled petroleum to get kerosene for
lamp oil, and threw away (!) the gasoline and naphtha, which had little use
before the invention of the internal combustion engine.

The two CAS items are similar light petroleum distillates resulting from
different processes. No doubt this is to let them to optimize different
raw materials depending on the market or availability.

I did a brief google search for the two items, and came to the
conclusion that the "Napthenic petroleum distillate" was a distillation
fraction somewhat lighter than kerosene - indeed, naptha, whereas
"petroleum base oil" was a light lubricating oil with a rather
higher boilpoint than kerosene.

Yeah, the terminology drives you nuts.

I had a summer job in a refinery for several years, testing the stuff
they produced. [Distillation curves, viscosity, pen tests,
flash points, etc.]

Meanwhile, earning a scholarship in chemistry. I think I knew more
chemistry than the permanent employees in the lab who'd been there
in some cases for decades. And I still couldn't make sense out
of the names. Rubber solvent? Wha?

In this particular refinery, I believe they called "naptha"
light kerosene.

In the sinks, the two faucets ran rubber solvent and varsol (I
now forgot what they called _that_) for cleaning the glassware.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.