received by the International Bureau on 17 September 2018 (17.09.2018)

1. A lubricating oil comprising a base oil mixture, wherein the base oil mixture comprises a lubricating oil base stock selected from the group consisting of a Group Π base stock, a Group ΠΙ base stock, a Group IV base stock and combinations thereof as a major component; and at least one cobase stock selected from the group consisting of C28 methyl paraffin, decyl palmitate, coconut oil and CI 8 dimer as a minor component at from 1 to 15 t.% of the lubricating oil having a kinematic viscosity (KvlOO) of less than about 6.2 cSt at 100°C, to reduce kinematic viscosity (KvlOO) of the base oil mixture as determined by ASTM D445, while maintaining or controlling cold cranking simulator viscosity (CCSV) of the lubricating oil as determined by ASTM D5293-15, such that the lubricating oil meets both kinematic viscosity (KvlOO) and cold cranking simulator viscosity (CCSV) requirements for a SAE engine oil grade as determined by SAE J300 viscosity grade classification system.

2. The lubricating oil of claim 1 which is a SAE 5W-20 engine oil, a SAE 5W-30 engine oil, or a SAE 10W-30 engine oil.

3. The lubricating oil of claim 1 in which kinematic viscosity (KvlOO) of the base oil mixture as determined by ASTM D445 is reduced, as compared to kinematic viscosity (KvlOO) of a base oil mixture containing a minor component other than the cobase stock, the lubricating oils having comparable cold cranking simulator viscosities (CCSVs) as determined by ASTM D5293-15 and high temperature high shear (HTHS) viscosities as determined by ASTM D4683-13.

4. The lubricating oil of claim 3 wherein the kinematic viscusiiy (KvlOO) u Liie base oil mixture as determined by ASTM D445 is reduced by greater than about 0.5 cSt.

5. The lubricating oil of claim 1 in which Noack volatility of the lubricating oil as determined by ASTM D5800 is reduced, as compared to Noack volatility of a lubricating oil containing a minor component other than the cobase stock, the lubricating oils having comparable cold cranking simulator viscosities (CCSVs) as determined by ASTM D5293-15 and high temperature high shear (HTHS) viscosities as determined by ASTM D4683-13.

6. The lubricating oil of claim 5 wherein the Noack volatility of the lubricating oil as determined by ASTM D5800 is reduced by about 0.5 to about 2.5 weight percent.

7. The lubricating oil of claim 1 which has a kinematic viscosity KvlOO) from about 2 cSt to about 12 cSt at 100°C as determined by ASTM D445, a cold cranking simulator viscosity (CCSV) at -35°C from about 1000 cP to about 6200 cP as determined by ASTM D5293-15, a cold cranking simulator viscosity (CCSV) at - 30°C from about 1000 cP to about 6600 cP as determined by ASTM D5293-15, a cold cranking simulator viscosity (CCSV) at -25°C from about 1000 cP to about 7000 cP as determined by ASTM D5293-15, and a high temperature high shear (HTHS) viscosity of less than about 3.5 cP as determined by ASTM D4683-13.

8. The lubricating oil of claim 1 having a viscosity index (VI) from about 80 to about 300 as determined by ASTM D2270, and a Noack volatility of no greater than 25 percent as determined by ASTM D5800.

9. The lubricating oil of claim 1 which has a MTM traction reduction of greater than about 5% as compared to MTM traction of a lubricating oil containing a minor component other than the cobase stock, as determined by the MTM (Mini Traction Machine) traction test.

10. The lubricating oil of claim 1 which further comprises one or more of a viscosity improver, antioxidant, detergent, dispersant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive.

11. The lubricating oil of claim 1 wherein the lubricating oil base stock is present in an amount from about 88 weight percent to about 98 weight percent, and the cobase stock is present in an amount from about 2 weight percent to about 12 weight percent, based on the total weight of the lubricating oil.

12. The lubricating oil of claim 1 which is a passenger vehicle engine oil (PVEO) or a commercial vehicle engine oil (CVEO).

13. The lubricating oil of claim 1 wherein the coconut oil is hydrogenated to reduce the level of unsaturated acid components.

14. A method for improving fuel efficiency and energy efficiency, while maintaining or improving deposit control and cleanliness performance, in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil, said formulated oil comprising a base oil mixture, wherein the base oil mixture comprises a lubricating oil base stock selected from the group consisting of a Group II base stock, a Group ΠΙ base stock, a Group IV base stock and combinations thereof as a major component; and at least one cobase stock selected from the group consisting of C28 methyl paraffin, decyl palmitate, coconut oil and C18 dimer as a minor component at from 1 to 15 wt.% of the lubricating oil having a kinematic viscosity (KvlOO) of less than about 6.2 cSt at 100°C, to reduce kinematic viscosity (KvlOO) of the base oil mixture as determined by ASTM D445, while maintaining or controlling cold cranking simulator viscosity (CCSV) of the lubricating oil as determined by ASTM D5293-15, such that the lubricating oil meets both kinematic viscosity (KvlOO) and cold cranking simulator viscosity (CCSV) requirements for a SAE engine oil grade as determined by SAE J300 viscosity grade classification system; and wherein fuel efficiency and energy efficiency are improved and deposit control and cleanliness performance are maintained or improved as compared to fuel efficiency, energy efficiency, deposit control and cleanliness performance achieved using a lubricating oil containing a minor component other than the cobase stock, the lubricating oils having comparable cold cranking simulator viscosities (CCSVs) as determined by ASTM D5293-15 and high temperature high shear (HTHS) viscosities as determined by ASTM D46S3-13.

15. The method of claim 14 wherein the lubricating oil is a SAE 5W-20 engine oil, a SAE 5W-30 engine oil, or a SAE 10W-30 engine oil.

16. The method of claim 14 in which kinematic viscosity (KvlOO) of the base oil mixture as determined by ASTM D445 is reduced, as compared to kinematic viscosity (KvlOO) of a base oil mixture containing a minor component other than the cobase stock, the lubricating oils having comparable cold cranking simulator viscosities (CCSVs) as determined by ASTM D5293-15 and high temperature high shear (HTHS) viscosities as determined by ASTM D4683-13.

17. The method of claim 14 wherein the kinematic viscosity (KvlOO) of the base oil mixture as determined by ASTM D445 is reduced by greater than about 0.5 cSt.

18. The method of claim 14 in which Noack volatility of the lubricating oil as determined by ASTM D5800 is reduced, as compared to Noack volatility of a lubricating oil containing a minor component other than the cobase stock, the lubricating oils having comparable cold cranking simulator viscosities (CCSVs) as determined by ASTM D5293-15 and high temperature high shear (HTHS) viscosities as determined by ASTM D4683-13.

19. The method of claim 18 wherein the Noack volatility of the lubricating oil as determined by ASTM D5800 is reduced by about 0.5 to about 2.5 weight percent.

20. The method of claim 14 wherein the lubricating oil has a kinematic viscosity (KvlOO) from about 2 cSt to about 12 cSt at 100°C as determined by ASTM D445, a cold cranking simulator viscosity (CCSV) at -35°C from about 1000 cP to about 6200 cP as determined by ASTM D5293-15, a cold cranking simulator viscosity (CCSV) at -30°C from about 1000 cP to about 6600 cP as determined by ASTM D5293-15, a cold cranking simulator viscosity (CCSV) at -25°C from about 1000 cP to about 7000 cP as determined by ASTM D5293-15, and a high temperature high shear (HTHS) viscosity of less than about 3.5 cP as determined by ASTM D4683 13.

21. The method of claim 14 wherein the lubricating oil has a viscosity index (VI) from about 80 to about 300 as determined by ASTM D2270, and a Noack volatility of no greater than 25 percent as determined by ASTM D5800.

22. The method of claim 14 wherein the lubricating oil has a MTM traction reduction of greater than about 5% as compared to MTM traction of a lubricating oil containing a minor component other than the cobase stock, as determined by the MTM (Mini Traction Machine) traction test.

23. The method of claim 14 wherein the lubricating oil further comprises one or more of a viscosity improver, antioxidant, detergent, dispersant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive.

24. (Formerly claim 40, currently amended): The method of claim 14 [[24]] wherein the lubricating oil base stock is present in an amount from about 88 weight percent to about 98 weight percent, and the cobase stock is present in an amount from about 2 weight percent to about 12 weight percent, based on the total weight of the lubricating oil.

25. The method of claim 14 wherein the lubricating oil is a passenger vehicle engine oil (PVEO) or a commercial vehicle engine oil (CVEO).

26. The method of claim 14 wherein the coconut oil is hydrogenated to reduce the level of unsaturated acid components.