Gasoil D2 - Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue. Fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash point of approximately 40 °C (104 °F) and oils burned in cotton or wool-wick burners. In this sense, diesel is a type of fuel oil. Fuel oil is made of long hydrocarbon chains, particularly alkanes, cycloalkanes and aromatics. The term fuel oil is also used in a stricter sense to refer only to the heaviest commercial fuel that can be obtained from crude oil, heavier than gasoline and naphtha.
"Low sulphur Gasoil" is no longer 4 percent - but below 0.2 percent. Then we have a new, "Ultra Low Sulphur" at 0.02% at the most, and the limit here is (a) that mass spectographs requires extensive calibration to measure below 1000ppm, and (b) sulphur has a way to form clogs - the molecules binds to free hydrogen molecules and form a cluster of molecules that will break if "cracked" by the refinery, but as explained above, D2 is a distillate and has not been "cracked". So - take a pint of ULSG, you may have the misfortune of having 0.1 percent sulphur - but the average for a barrel will be less then 0.02 - its just you managed to get a cluster of molecules
The GOST variant for D2/Gasoil is GOST 305-82 and specifies now a sulphur content of 0.02 MAX which is according to the ISO standard. However, the ANSI standard will call this "Ultra Low Sulphur", and retain 0,2% (2000ppm) as the "Low sulphur. The reduction of sulphur in the Gasoil used for heating has contributed to less pollution in many cities.