Patent ID: 8628592

Claim:
A method of producing a gas oil composition comprising steps of: preparing a gas oil composition (B) comprising an FT synthetic base oil in an amount of 60 percent by volume or more on the basis of the total amount of the gas oil composition (B); and then (Step 1) adding to the gas oil composition (B) by line-blending, forced-stirring or leaving to stand for a sufficient time a lubricity improver comprising a fatty acid and/or a fatty acid ester in an amount of 20 mg/L or more and 300 mg/L or less in terms of the active component on the basis of the total amount of the gas oil composition (B), and subsequently (Step 2) adding to the gas oil composition (B) by line-blending, forced-stirring or leaving to stand for a sufficient time a cold flow improver comprising an ethylene vinyl acetate copolymer and/or a compound with a surface active effect in an amount of 20 mg/L, or more and 1000 mg/L or less in terms of the active component on the basis of the total amount of the gas oil composition (B), wherein the gas oil composition has a sulfur content of 5 ppm by mass or less, an aromatic content of 1 percent by volume or less, an oxygen content of 100 ppm or less, a density at 15° C. of 760 kg/m 3 or greater and 840 kg/m 3 or less, a 90% distillation temperature of 280° C. or higher and 350° C. or lower and an end point of 360° C. or lower in distillation characteristics, a total insoluble content after an oxidation stability test of 0.5 mg/100 mL or less, an HFRR wear scar diameter (WS1.4) of 400 μm or smaller, a cloud point of −5° C. or lower, a cold filter plugging point of −20° C. or lower, a pour point of −25° C. or lower, a total content of normal paraffins having 20 to 30 carbon atoms of 2 percent by mass or more and less than 4 percent by mass, a ratio of a total content of 20 to 30 carbon atoms normal paraffins to a total content of hydrocarbons other than the 20 to 30 carbon atom normal paraffins of 0.2 or greater and 0.6 or less, and a relation in the content of each of normal paraffins (CnP) having 20 to 25 carbon atoms defined by C20P>C21P>C22P>C23P>C24P>C25P.