1. John R. Lindsay Smith, Moray S. Stark,* Julian J. Wilkinson Department of Chemistry, University of York, York YO10 5DD, UK Peter M. Lee, Martin Priest School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK R. Ian Taylor Shell Global Solutions, Chester, CH1 3SH, UK Simon Chung Infineum UK Ltd., Milton Hill, Abingdon, Oxfordshire, OX13 6BB, UK Additives 2005 : Dublin 5 th - 7 th April 2005 The Degradation of Lubricants in Gasoline Engines Department of Chemistry

2. John R. Lindsay Smith, Moray S. Stark,* Julian J. Wilkinson Department of Chemistry, University of York, York YO10 5DD, UK Peter M. Lee, Martin Priest School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK R. Ian Taylor Shell Global Solutions, Chester, CH1 3SH, UK Simon Chung Infineum UK Ltd., Milton Hill, Abingdon, Oxfordshire, OX13 6BB, UK The Degradation of Lubricants in Gasoline Engines mss1@york.ac.uk www.york.ac.uk/res/gkg Additives 2005 : Dublin 5 th - 7 th April 2005

3. Understand Increase in Engine Friction with Oil Degradation Department of Chemistry The Degradation of Lubricants in Gasoline Engines

4. Understand Increase in Engine Friction with Oil Degradation  Sampling of Lubricant from Piston Assembly Department of Chemistry The Degradation of Lubricants in Gasoline Engines

5. Understand Increase in Engine Friction with Oil Degradation  Sampling of Lubricant from Piston Assembly  Measurement of Lubricant Flow in Engine Department of Chemistry The Degradation of Lubricants in Gasoline Engines

6. Understand Increase in Engine Friction with Oil Degradation  Sampling of Lubricant from Piston Assembly  Measurement of Lubricant Flow in Engine  Measurement of Lubricant Degradation in Engine Department of Chemistry The Degradation of Lubricants in Gasoline Engines

7. Understand Increase in Engine Friction with Oil Degradation  Sampling of Lubricant from Piston Assembly  Measurement of Lubricant Flow in Engine  Measurement of Lubricant Degradation in Engine  Chemical Mechanisms of Base Fluid Oxidation Department of Chemistry The Degradation of Lubricants in Gasoline Engines

8. Viscosity Increase in a Paris Taxi Fleet The Degradation of Lubricants in Gasoline Engines Department of Chemistry

9. Engine Oil Stress Factor for Gasoline Cars : 1950 - 2000 The Degradation of Lubricants in Gasoline Engines R. I. Taylor, R. Mainwaring, R. M. Mortier, Engine Lubricant Trends Since 1990, Proc. I. Mech. E. Vol 219, Part J: J. Engineering Tribology, p 1-16, 2005 © BP Castrol

10. Engine : Ricardo Hydra Institute of Tribology School of Mechanical Engineering,The University of Leeds Department of Chemistry  Fuel Injected Gasoline  Single Cylinder  0.5 litre Capacity

11. Lubrication of Engine P. M. Lee, M. Priest, J. R. Lindsay Smith, M. S. Stark, J. J. Wilkinson, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press)

12. Lubrication of Engine P. M. Lee, M. Priest, J. R. Lindsay Smith, M. S. Stark, J. J. Wilkinson, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press)

13. Lubrication of Engine P. M. Lee, M. Priest, J. R. Lindsay Smith, M. S. Stark, J. J. Wilkinson, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press) Sump 1 Valve Train

14. Lubrication of Engine P. M. Lee, M. Priest, J. R. Lindsay Smith, M. S. Stark, J. J. Wilkinson, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press) Sump 1 Valve Train Sump 2 Piston Assembly Crank Shaft

15. Lubrication of Engine P. M. Lee, M. Priest, J. R. Lindsay Smith, M. S. Stark, J. J. Wilkinson, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press) Sump 2 Piston Assembly Crank Shaft

16. Degradation of Lubricant Piston Assembly Sump P. M. Lee, M. Priest, J. R. Lindsay Smith, M. S. Stark, J. J. Wilkinson, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press)

17. Degradation of Lubricant S. Yasutomi, Y. Maeda and T. Maeda, Kinetic Approach To Engine Oil.2. Antioxidant Decay of Lubricant in Engine System, Ind. Eng. Chem. Prod. Res. Dev. 20 (1981) 536 Piston Assembly Sump Piston Sump

18. Piston Assembly R. Gamble, Influence of Lubricant Degradation on Piston Assembly Tribology, PhD Thesis, University of Leeds, 2002

19. Piston Assembly M. S. Stark, R. J. Gamble, C. J. Hammond et al., Measurement of Lubricant Flow in a Gasoline Engine, Tribology Letters (in press) 2005

20. Extraction of Oil from Top Piston Ring R. Gamble, Influence of Lubricant Degradation on Piston Assembly Tribology, PhD Thesis, University of Leeds, 2002

21. Extraction of Oil from Top Piston Ring P. M. Lee, M. Priest, J. R. Lindsay Smith, M. S. Stark, J. J. Wilkinson, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press)

22. Oil Flow in Engine Small Volume Short Residence Time Large Volume Long Residence Time Flow Rate S. Yasutomi, Y. Maeda and T. Maeda, Kinetic Approach To Engine Oil.2. Antioxidant Decay of Lubricant in Engine System, Ind. Eng. Chem. Prod. Res. Dev. 20 (1981) 536 Sump Piston

23. Piston Assembly Residence Time: Method Sump Piston Add Marker to Sump S B Saville, F D Gainey, S D Cupples, M F Fox, D J Picken, SAE Technical Paper, International Fuels and Lubricants Meeting, Oct 10-13, 1988 Sample Lubricant from Piston Assembly

24. Piston Assembly Residence Time: Method 1-e -1  RingPac k S B Saville, F D Gainey, S D Cupples, M F Fox, D J Picken, SAE Technical Paper, International Fuels and Lubricants Meeting, Oct 10-13, 1988

25. Piston Assembly Residence Time : 60 sec M. S. Stark, R. J. Gamble, C. J. Hammond et al., Measurement of Lubricant Flow in a Gasoline Engine, Tribology Letters (in press) 2005 Conditions : 1500 rpm, 50 % Load. Lubricant : XHVI TM 8.2 only

26. Piston Flow Rate: Method Small Volume Short Residence Time Large Volume Long Residence Time Flow Rate S. Yasutomi, Y. Maeda and T. Maeda, Kinetic Approach To Engine Oil.2. Antioxidant Decay of Lubricant in Engine System, Ind. Eng. Chem. Prod. Res. Dev. 20 (1981) 536 Sump Piston

27. Oxidation Chemistry Hydrocarbon Base Fluid (schematic) Department of Chemistry

28. Oxidation Chemistry Hydrocarbon Base Fluid Hydroperoxides Department of Chemistry

29. Oxidation Chemistry Hydrocarbon Base Fluid Hydroperoxides Alcohols Department of Chemistry

30. Oxidation Chemistry Hydrocarbon Base Fluid Hydroperoxides Alcohols Carboxylic Acids Ketones Department of Chemistry

31. Oxidation Chemistry Infrared Spectroscopy of Carbonyl Group Hydrocarbon Base Fluid Hydroperoxides Alcohols Carboxylic Acids Ketones Department of Chemistry

32. Comparison of Sump and Ring Pack Conditions : 2000 rpm, 50 % Load M. S. Stark, J. J. Wilkinson, P. M. Lee, J. R. Lindsay Smith, M. Priest, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press)

33. Comparison of Sump and Ring Pack Conditions : 2000 rpm, 50 % Load M. S. Stark, J. J. Wilkinson, P. M. Lee, J. R. Lindsay Smith, M. Priest, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press)

34. Calculation of Sump Residence Time M. S. Stark, J. J. Wilkinson, P. M. Lee, J. R. Lindsay Smith, M. Priest, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press)

35. Calculation of Sump Residence Time M. S. Stark, J. J. Wilkinson, P. M. Lee, J. R. Lindsay Smith, M. Priest, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press)

36. Calculation of Sump Residence Time M. S. Stark, J. J. Wilkinson, P. M. Lee, J. R. Lindsay Smith, M. Priest, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press)

37. Sump Residence Time : Engine Speed Conditions : 1000 - 2000 rpm, 50 % Load M. S. Stark, J. J. Wilkinson, P. M. Lee, J. R. Lindsay Smith, M. Priest, R. I. Taylor and S. Chung, Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, Elsevier, 2005 (in press)

38. Piston Assembly Residence Time  60 seconds Volume of Oil  1 cm 3 cylinder -1 Flow Rates Returning to Sump  1 cm 3 min -1 cylinder -1 Oil Loss  0.05 cm 3 min -1 cylinder -1 Sump Residence Time  20 hours litre -1 Characterisation of Gasoline Engine M. S. Stark, R. J. Gamble, C. J. Hammond, et al., Tribology Letters, (in press) 2005 M. S. Stark, et al., Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, (in press) 2005

39. Piston Assembly Residence Time  60 seconds Volume of Oil  1 cm 3 cylinder -1 Temperature  200 °C Flow Rates Returning to Sump  1 cm 3 min -1 cylinder -1 Oil Loss  0.05 cm 3 min -1 cylinder -1 Sump Residence Time  20 hours litre -1 Temperature  70 °C Characterisation of Gasoline Engine M. S. Stark, R. J. Gamble, C. J. Hammond, et al., Tribology Letters, (in press) 2005 M. S. Stark, et al., Proceedings of the 31st Leeds-Lyon Symposium on Tribology, Sept 2004, (in press) 2005

40. No. of Carbons XHVI™ 8.2 (average) 39 (random example) Hydrocarbon Degradation Chemistry Department of Chemistry

41. No. of Carbons XHVI™ 8.2 (average) 39 Hexadecane16 (random example) Models of Hydrocarbon Base-Fluids Department of Chemistry

42. Traditional Alkane Oxidation Mechanism

43. Department of Chemistry Traditional Alkane Oxidation Mechanism

44. Department of Chemistry Traditional Alkane Oxidation Mechanism

45. Department of Chemistry Traditional Alkane Oxidation Mechanism

46. Department of Chemistry Traditional Alkane Oxidation Mechanism

47. Department of Chemistry Traditional Alkane Oxidation Mechanism

48. Hexadecane Oxidation Jensen et al, J. Am. Chem. Soc., 103, 1742 1981 and 101, 7574 1979 (Conditions : 120 – 180 °C)

49. Hexadecane Oxidation Jensen et al, J. Am. Chem. Soc., 103, 1742 1981 and 101, 7574 1979 (Conditions : 120 – 180 °C)

50. Hexadecane Oxidation Jensen et al, J. Am. Chem. Soc., 103, 1742 1981 and 101, 7574 1979 (Conditions : 120 – 180 °C)

51. Hexadecane Oxidation Jensen et al, J. Am. Chem. Soc., 103, 1742 1981 and 101, 7574 1979 (Conditions : 120 – 180 °C)

52. Hexadecane Oxidation Jensen et al, J. Am. Chem. Soc., 103, 1742 1981 and 101, 7574 1979 (Conditions : 120 – 180 °C)

53. No. of Carbons XHVI™ 8.2 (average) 39 Hexadecane16 Pristane 19 (random example) Models of Hydrocarbon Base-Fluids Department of Chemistry

54. No. of Carbons XHVI™ 8.2 (average) 39 Hexadecane16 Pristane 19 Squalane30 (random example) Models of Hydrocarbon Base-Fluids Department of Chemistry

55. Tertiary Carbons in Base-Fluids S. McKenna, M. Casserino, K. Ratliff, Comparing the Tertiary Carbon Content of PAO’s and Mineral Oils Presentation, STLE Annual Meeting, Houston, 2002

56. Tertiary Carbons in Base-Fluids S. McKenna, M. Casserino, K. Ratliff, Comparing the Tertiary Carbon Content of PAO’s and Mineral Oils Presentation, STLE Annual Meeting, Houston, 2002

57. Bench-Top Reactors Department of Chemistry

58. time (min) Solvent (CH 3 OH) Oxidation of Pristane : GC Analysis (polar) Department of Chemistry Micro-reactor conditions: 1000 mbar O 2, 200 ºC, 1 minute GC conditions: Carbowax column, 50-250 ºC, 4 ºC min -1

59. time (min) Department of Chemistry Oxidation of Pristane : GC (non-polar) impurity Micro-reactor conditions: 1000 mbar O 2, 200 ºC, 1 minute GC conditions: ZB-5 column, 50-300 ºC, 6 ºC min -1

60. time (min) Ketones impurity Department of Chemistry Oxidation of Pristane : Ketones

61. time (min) Department of Chemistry impurity Oxidation of Pristane : Ketones

62. time (min) Alkane Department of Chemistry Oxidation of Pristane : Alkanes

63. time (min) + RH Department of Chemistry Oxidation of Pristane : Fragmentation

64. time (min) Department of Chemistry Oxidation of Pristane : Fragmentation +

65. time (min) Department of Chemistry Oxidation of Pristane : Fragmentation +

66. Department of Chemistry Reactions of Alkyl Radicals

67. Department of Chemistry Reactions of Alkyl Radicals

68. Department of Chemistry Reactions of Alkyl Radicals

69. Department of Chemistry Reactions of Alkyl Radicals

70. Department of Chemistry Formation of Carboxylic Acids

71. Department of Chemistry Formation of Carboxylic Acids

72. Department of Chemistry Formation of Carboxylic Acids

73. Department of Chemistry Formation of Carboxylic Acids

74. time (min) Department of Chemistry Oxidation of Pristane : Alkenes

75. Department of Chemistry Possible Mechanisms of Alkene Formation

76. Department of Chemistry Possible Mechanisms of Alkene Formation

77. Department of Chemistry Possible Mechanisms of Alkene Formation

78. Department of Chemistry Possible Mechanisms of Alkene Formation

79. Department of Chemistry Possible Mechanisms of Alkene Formation

80. Department of Chemistry Alkenes and Polymerisation (+ ROO.)

81. Department of Chemistry Alkenes and Polymerisation (+ ROO.)

82. Department of Chemistry Alkenes and Polymerisation (+ ROO.)

83. Conclusions  Sampling of Lubricant from Piston Assembly  Measurement of Lubricant Flow in Engine  Measurement of Lubricant Degradation in Engine  Chemical Mechanisms of Base Fluid Oxidation Department of Chemistry

84. Project Posters  Peter Lee Lubricant Degradation Studies Using a Single Cylinder Research Engine Engine Set-up and Modifications  Julian Wilkinson Understanding Lubricant Degradation in Gasoline Engines Oxidation Mechanisms of Model Base Fluids Viscosity Change During Hydrocarbon Oxidation Department of Chemistry

85. Acknowledgements University of LeedsRichard Gamble, Chris Taylor, D. Desmonteix University of YorkChris Hammond, David Waddington, Trevor Dransfield ShellHarold Gillespie, Eiji Nagatomi, Richard Dixon InfineumBénédicte Menguy Financial Support Shell Global Solutions, Infineum, EPSRC Moray Stark mss1@york.ac.uk www.york.ac.uk/res/gkg

86. The Degradation of Lubricants in Gasoline Engines (Abstract for Additives 2005 : Dublin 5th- 7th April 2005) Moray S. Stark*, John R. Lindsay Smith, Julian J. Wilkinson, Department of Chemistry, University of York, York YO10 5DD, UK Peter M. Lee, Martin Priest, School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK R. Ian Taylor, Shell Global Solutions, Shell Research Ltd, PO Box 1, Chester, CH1 3SH, UK Simon Chung, Infineum UK Limited, PO Box 1, Milton Hill, Abingdon, Oxfordshire, OX13 6BB, UK Automotive engines contribute significantly to the global anthropogenic emission of the greenhouse gas, CO 2. Consequently, forthcoming legislation on engine lubricants will place high demands on fuel economy, and require its retention as the oil is degraded by use. The project discussed here is a collaboration between tribologists and chemists with the aim being to achieve a greater understanding of this loss in engine efficiency due to lubricant thickening with use. To do this it is first necessary to understand the factors that control the rate of degradation of a lubricant, as well as the type and quantity of oxidation products that are formed. It is then necessary to understand the rheology of degrading lubricant; how the oxidation products formed change the viscosity as the oil ages. Finally, it is required to understand the tribology of the problem, i.e. how the increase in lubricant viscosity with use affects piston friction, and thereby the efficiency of the engine. This presentation will give an overview of the project, as well as details of the chemical degradation and rheological changes that a lubricant experiences with use. Lubricant has been degraded in both in a research gasoline engine, and in bench-top reactors designed to mimic the conditions that a lubricant experiences in the piston assembly. The chemical degradation model being developed considers in detail the attack on a hydrocarbon base fluid by free radicals formed by the oxidation process, with separate attack on secondary and tertiary hydrogen atoms. The subsequent oxidation of these free radicals to form degradation products such as carboxylic acids, alcohols, ketones and alkenes is also described in detail. This chemical model has been refined by comparison with experiments in bench-top reactors on the oxidation of Group III lubricant base fluids, and structurally simpler analogues of hydrocarbon base fluids (squalane (C 30 H 62 ) and tetramethylpentadecane). Measurements of the lubricant degradation in, and flow of lubricant through, the piston assembly of a gasoline engine have been made; this information is necessary for the modelling of chemical degradation in an engine, and simulations of the lubricant degradation in an engine using the chemical model are compared with experiment. The modelling of rheological changes due to lubricant degradation is at an earlier stage of development, and work will be reported on the simulation of viscosity increase during the oxidation in bench top reactors of chemical analogues of hydrocarbon base fluids. * Biography for Presenting Author Moray Stark has a BSc and PhD in Physics, but has been working as a Chemist for longer than he can remember. The past few years have been spent specialising in the study of the oxidation mechanisms of hydrocarbon and ester lubricant base fluids, and the effects that oxidation products have on the rheology of lubricants. This work is sponsored by Shell Global Solutions (UK) and Infineum.