While other navies used highly refined burner oil, in the last stages of World War II the Imperial Japanese Navy was directly using high quality crude oil obtained from the captured East Indian colonial possessions of the Netherlands and France. While quite functional as a boiler fuel, this crude carried a hazard; as the lighter fractions had not been distilled out they formed highly flammable vapors within the warships' fuel tanks. This would often lead to a tank compartment explosion during battle should a shell penetrate the compartment or venting lines.
Previously at Pacific War, since 30s period, Navy along Japanese Government, acquired German state manufacture license for installing the shale plant in Fushun, Manchukuo was perhaps capable of annual production of 200,000 tons of shale oil. The Imperial Japanese Navy also had an interest there in producing some diesel oil and gasoline, in low amounts, with some little shale extraction in Jehol province. Later such production was ampled with petrol pits recent acquired in Dutch Indies, French Indochina and Burma during wartimes.