TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Property: The lubricating oil composition has dynamic viscosity of 10-100 mm2/second, viscosity index of 80 or more, and aromatic component content of 10 wt.% or less measured by column chromatography analysis.Preferred Process: The lubricating oil composition is obtained by mixing mineral oil fraction (in wt.%) (5-95) having 50% distillation temperature of 200-350degreesC measured by gas chromatography method-distillation test method, and mineral oil fraction (95-5) having aniline point of 50degreesC or more, and 50% distillation temperature of 400degreesC or more.Preferred Composition: The lubricating oil composition further contains abrasion resistance agent(s) (0.05-1.5) containing phosphoric acid derivative (triphenyl phosphate or tricresyl phosphate), sulfur compound (thiobis phenol) or oxygen-containing compound (glycerol mono olate, glycerol monooleyl ether, glycidyl ether and glycidyl ester). EXAMPLE - A mineral oil fraction (A) had 50% distillation temperature (DT) of 345degreesC measured by gas chromatography method-distillation test method according to ASTM D 2887-02, dynamic viscosity of 30.7 mm2/second, 7.1 mm2/second and 2.18 mm2/second at 0degreesC, 40degreesC and 100degreesC, respectively, and viscosity index of 112, measured according to JIS K 2283-1993, and aniline point of 102degreesC measured according to JIS K 2256-1998. A mineral oil fraction (B) had DT of 274degreesC, dynamic viscosity of 21 mm2/second, 5.2 mm2/second and 1.7 mm2/second at 0degreesC, 40degreesC and 100degreesC, respectively, and aniline point of 70degreesC. Mineral oil fractions (A) (in wt.%) (85) and (B) (15) were mixed to obtain a lubricating oil. The lubricating oil had dynamic viscosity of 39.6 mm2/second at 0degreesC, sulfur content of 119 ppm measured according to JIS K 2541-1996, aniline point of 102degreesC, viscosity index of 110, aromatic component content of 3.3 wt.% measured according to ASTM D 2549-02 and total acid number of 0.17 measured according to JIS K 2501-2003. The oil suppressed sludge generation and abrasion of sliding portion, and reduced power consumption.