Soot control for diesel engine lubricants

Abstract

The present invention is directed to a method for controlling soot induced viscosity increase in diesel engines, by using as the diesel engine lubricant an oil formulation comprising a base oil containing about 10 to 80 wt % GTL base stock and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base stock and/or base oil in combination with 20 to 90 wt % conventional Group I petroleum derived base oil, said base oil being further combined with a polymeric viscosity modifier, and to the lubricating oil which effects such control over soot induced viscosity increase.

Description

DESCRIPTION OF THE FIGURES

FIG. 1 shows the relationship between % viscosity increase due to soot and the GTL content of the base oil.

FIG. 2 shows the relationship between thickening ability attributable to Viscosity Modifier and the GTL content of the base oil.

FIG. 3 shows the interrelationship between % viscosity increase due to soot and the thickening ability attributable to the viscosity modifier at different GTL levels in the base oil.

Claims

1. A method for controlling the soot induced viscosity increase of conventional/mineral oil derived base stock or base oil lubricating oils used in diesel engines during use by adding to the lubricating oil about 10 to 80 wt % of a GTL base stock and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base stock or base oil, based on the weight of the total base oil.

2. A method for controlling the soot induced viscosity increase of lubricating oils used in diesel engines during use by employing as the diesel engine lubricating oil an oil formulation comprising a base stock or base oil containing about 10 to 80 wt % of a GTL base stock and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base stock and/or base oil in combination with about 90 to 20 wt % of a conventional petroleum/mineral oil derived base stock, based on the weight of the total base oil.

3. The method of claim 1 or 2 wherein the amount of GTL base stock and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base stock and/or base oil is in the range of about 10 to 70 wt % based on the weight of the total base oil.

4. The method of claim 1 or 2 wherein the conventional petroleum/mineral oil derived base stock is a Group I and/or Group II base stock.

5. The method of claim 4 wherein the conventional petroleum/mineral oil derived base stock is a Group I base stock.

6. The method of claim 1 or 2 wherein the GTL base stock and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base stock and/or base oil has a kinematic viscosity at 100° C. in the range of about 2 to 50 mm2/s.

7. The method of claim 1 or 2 wherein the GTL base stock and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base stock and/or base oil has a kinematic viscosity at 100° C. in the range of about 3 to 40 mm2/s.

8. The method of claim 1 or 2 wherein the GTL base stock and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base stock and/or base oil has a kinematic viscosity at 100° C. in the range of about 3.5 to 30 mm2/s.

9. The method of claim 2 wherein the conventional petroleum/mineral oil derived base stock has a kinematic viscosity at 100° C. in the range of about 2 to 20 mm2/s.

10. The method of claim 4 wherein the conventional petroleum/mineral oil derived base stock has a kinematic viscosity at 100° C. in the range of about 4 to 10 mm2/s.

11. The method of claim 5 wherein the conventional petroleum/mineral oil derived base stock has a kinematic viscosity at 100° C. in the range of about 4 to 8 mm2/s.

12. The method of claim 1 or 2 wherein the GTL base stock and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base stock and/or base oil has a kinematic viscosity at 100° C. in the range of about 3.5 to 30 mm2/s and the conventional petroleum/mineral oil derived stock is a Group I and/or Group II stock which has a kinematic viscosity at 100° C. in the range of about 4 to 8 mm2/s.

13. A diesel engine lubricating oil formulation resistant to soot induced viscosity increase during use comprising a base oil containing about 10 to 80 wt % GTL base stock and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base stock and/or base oil, about 90 to 20 wt % of a conventional petroleum/mineral oil derived base oil, based on the weight of the total base oil and about 1 to 25 wt % on an as received basis of a polymeric viscosity modifying additive, based on the total weight of the lubricating oil formulation.

14. The diesel engine lubricating oil formulation of claim 13 wherein the GTL base stock and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base stock and/or base oil comprises about 10 to 70 wt % of the total base oil.

15. The diesel engine lubricating oil formulation of claim 13 wherein the GTL base stock and/or base oil and/or hydrodewaxed or hydroisomerized/catalytic (or solvent) dewaxed base stock and/or base oil comprises about 10 to 60 wt % of the total base oil.

16. The diesel engine lubricating oil formulation of claim 13, 14 or 15 wherein the conventional petroleum/mineral oil derived base oil is a Group I and/or Group II base oil.

17. The diesel engine lubricating oil formulation of claim 16 wherein the base oil is a Group I base oil.

18. The diesel engine lubricating oil formulation of claim 13, 14 or 15 wherein the polymeric viscosity modifying additive is present in an amount in the range of about 5 to 25 wt % on an as received base, based on the total weight of the lubricating oil formulation.