Terminology: Light oil, Heavy oil, Petroleum gas

[befzz]

In real life we can't get a Light oil and Heavy oil from crude oil.

But we can get:

light distillates (LPG, gasoline, naphtha),
middle distillates (kerosene, jet fuel, diesel),
heavy distillates and residuum (heavy fuel oil, lubricating oils, wax, asphalt

Currently its mixed:
word-by-word (abstract item name, what misleading)
and some of the fraction names: Mazut and Diesel

So. how we should translate it?
What original idea was? (meaning of light/heavy oil)

Ver. 0.9.0 Changelog

Oil industry. Pumpjacks mine the crude oil from the oil spills. Oil refinery processes the crude oil to oil fractions. Chemical plant processes the oil fractions to useful products.

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p.s. russian translation