In addition to standard requirements to fractional composition and cetane number, diesel is subject to slightly different requirements than that applied to gasoline. After introduction of more stringent sulphur content requirements and improved treatment of diesel fraction, the composition of diesel fraction changed as it contained greater quantities of compounds which at lower temperatures tend to freeze. This worsened performance of diesel at low temperatures and put refineries under additional requirements.
In order to avoid operational problems, transitional periods were introduced and the composition of transitional and winter grade diesel was changed in essence. In addition to different process improvements, a lower-boiling-point component is added to diesel during transitional and winter seasons. In other words, it is diluted with kerosene. As it has lower fraction limits and density, it improves cold weather handling temperatures of diesel fuel. Kerosene has better cold filter plugging point (CFPP) than diesel which means it improves cold flow operability of diesel fuel blend and cold start.
Moreover, winter and transitional grades of diesel are produced without FAME. In fact, it results in some certain fuel consumption "increase". As density is smaller, one liter of fuel is lighter by weight or, in other words, has less energy therefore bigger quantity in liters is needed.
Diesel for agriculture is dyed and marked in accordance with requirements of State Tax Inspectorate.
Diesel for heating contains special dyes and markers.
Dyes are substances which give color to fuel. When fuel is diluted in big proportions, the color may go pale however with special reagents it is possible to determine exactly in what proportion dyed fuel was diluted.
Markers are substances which have color only in some certain conditions. Chemical indicators are an example of such substances. Therefore with the use of reagent fuel with markers also gets the color of dye. And again, from the content of marker it is possible to determine in what proportion marked fuel was diluted.