The lubricating oil composition according to the present invention is one including a base oil, (A) a substituted hydroxy aromatic carboxylic acid ester derivative represented by at least one of the general formula (I) and the general formula (II), and (B) a heterocyclic compound represented by the general formula (III) or (IV) blended therein, wherein a phosphorus content is 0.06 mass % or less on the basis of a total amount of the composition, and a sulfated ash content is 1.2 mass % or less on the basis of a total amount of the composition. The lubricating oil composition is capable of maintaining high-temperature detergency and acid neutralizing properties, even when amounts of a phosphorus component-containing additive and a metallic detergent are reduced.

The lubricating oil composition according to the present invention is one including a base oil, (A) a substituted hydroxy aromatic carboxylic acid ester derivative represented by at least one of the general formula (I) and the general formula (II), and (B) a heterocyclic compound represented by the general formula (III) or (IV) blended therein, wherein a phosphorus content is 0.06 mass % or less on the basis of a total amount of the composition, and a sulfated ash content is 1.2 mass % or less on the basis of a total amount of the composition. The lubricating oil composition is capable of maintaining high-temperature detergency and acid neutralizing properties, even when amounts of a phosphorus component-containing additive and a metallic detergent are reduced.

A lubricating oil composition for an internal combustion engine, the composition including: a lubricating base oil comprising at least one mineral base oil or at least one synthetic base oil or any combination thereof, the lubricating base oil having a kinematic viscosity at 100° C. of 4.0 to 4.5 mm.sup.2/s and a NOACK evaporation loss at 250° C. of no more than 15 mass %; (A) a calcium-containing metallic detergent in an amount of no less than 1000 mass ppm and less than 2000 mass ppm in terms of calcium on the basis of the total mass of the composition; and optionally (C) a viscosity index improver in an amount of less than 1 mass % on the basis of the total mass of the composition.

A lubricating oil composition for an internal combustion engine, the composition including: a lubricating base oil comprising at least one mineral base oil or at least one synthetic base oil or any combination thereof, the lubricating base oil having a kinematic viscosity at 100° C. of 4.0 to 4.5 mm.sup.2/s and a NOACK evaporation loss at 250° C. of no more than 15 mass %; (A) a calcium-containing metallic detergent in an amount of no less than 1000 mass ppm and less than 2000 mass ppm in terms of calcium on the basis of the total mass of the composition; and optionally (C) a viscosity index improver in an amount of less than 1 mass % on the basis of the total mass of the composition.

A process for producing a base oil composition from a deasphalted oil (DAO) feed, where the DAO feed undergoes hydrotreating, hydrocracking, catalytically dewaxing, hydrofinishing, and fractionating to generate the base oil composition. The base oil composition includes a hazy-free at 0° C. heavy base oil comprising (a) a kinetic viscosity ranging from 15 to 21 cSt at 100° C., (b) a 5 viscosity index of at least 95, (c) a pour point of less than −12° C., (d) a cloud point of less than −18° C., and (e) a total aromatics content of 2 wt % or less, where the hazy-free at 0° C. heavy base oil maintains a hazy-free appearance when stored undisturbed at 0° C. during a test period.

A process for producing a base oil composition from a deasphalted oil (DAO) feed, where the DAO feed undergoes hydrotreating, hydrocracking, catalytically dewaxing, hydrofinishing, and fractionating to generate the base oil composition. The base oil composition includes a hazy-free at 0° C. heavy base oil comprising (a) a kinetic viscosity ranging from 15 to 21 cSt at 100° C., (b) a 5 viscosity index of at least 95, (c) a pour point of less than −12° C., (d) a cloud point of less than −18° C., and (e) a total aromatics content of 2 wt % or less, where the hazy-free at 0° C. heavy base oil maintains a hazy-free appearance when stored undisturbed at 0° C. during a test period.

The present disclosure provides a lubricating oil composition which is excellent in metal fatigue life, wear resistance and electrical insulating properties, even when the composition has a reduced viscosity. The lubricating oil composition according to the present disclosure comprises: (A) a lubricating base oil; (B) from 0.6 to 4.0% by weight, based on the total weight of the lubricating oil composition, of a polydiene having a number average molecular weight of from 500 to 3,000 and containing a functional group on at least one end thereof; and (C) at least one selected from a phosphorus-based anti-wear agent and a phosphorus-based extreme pressure agent, the at least one agent being contained in such an amount that the content of phosphorus is from 50 to 500 ppm by weight based on the total weight of the lubricating oil composition.

The present disclosure provides a lubricating oil composition which is excellent in metal fatigue life, wear resistance and electrical insulating properties, even when the composition has a reduced viscosity. The lubricating oil composition according to the present disclosure comprises: (A) a lubricating base oil; (B) from 0.6 to 4.0% by weight, based on the total weight of the lubricating oil composition, of a polydiene having a number average molecular weight of from 500 to 3,000 and containing a functional group on at least one end thereof; and (C) at least one selected from a phosphorus-based anti-wear agent and a phosphorus-based extreme pressure agent, the at least one agent being contained in such an amount that the content of phosphorus is from 50 to 500 ppm by weight based on the total weight of the lubricating oil composition.

A lubricating oil composition for an internal combustion engine includes: (A) a lubricating base oil including at least one mineral oil-based base oil and having a kinematic viscosity at 100° C. of from 2.0 mm.sup.2/s or more and 4.3 mm.sup.2/s or less, and (B) a calcium borate-containing metallic detergent in an mount of 500 mass ppm or more and less than 1500 mass ppm in terms of calcium, based on a total amount of the composition. The composition has an evaporation loss by NOACK method (250° C., 1 h) of from 10 mass % or more and 40 mass % or less, and the composition has a viscosity index of from 140 or more and 350 or less. The lubricating oil composition is provided, wherein even in the case of using a highly evaporative base oil to make the viscosity low, the friction characteristic of the lubricating oil composition can be kept low.

A lubricating oil composition for an internal combustion engine includes: (A) a lubricating base oil including at least one mineral oil-based base oil and having a kinematic viscosity at 100° C. of from 2.0 mm.sup.2/s or more and 4.3 mm.sup.2/s or less, and (B) a calcium borate-containing metallic detergent in an mount of 500 mass ppm or more and less than 1500 mass ppm in terms of calcium, based on a total amount of the composition. The composition has an evaporation loss by NOACK method (250° C., 1 h) of from 10 mass % or more and 40 mass % or less, and the composition has a viscosity index of from 140 or more and 350 or less. The lubricating oil composition is provided, wherein even in the case of using a highly evaporative base oil to make the viscosity low, the friction characteristic of the lubricating oil composition can be kept low.