1. PEI as a measure of ZDDP volatility in the engine 1 Phosphorus Emission Index (PEI) Studies Of ZDDP in Engine Oils ESCIT Meeting, 2006 May 4 At Afton Chemical Co., Richmond, Virginia Presented by: Ted Selby, Savant, Inc.

2. PEI as a measure of ZDDP volatility in the engine 2 In turn, this led to studies of factors limiting or reducing catalyst life and it was found and verified that the phosphorus present in ZDDP could enter the exhaust stream and form a coating on the catalyst surface that hindered catalyst effectiveness. For many years, ZDDP’s evident anti-wear and anti-oxidation effectiveness led to its being viewed as a necessary and desirable additive in formulating engine oils. History Growing government controls on automotive exhaust gas pollution control over the last half century more recently led to requirements for long exhaust catalyst life. With this finding, responses by those specifying engine oil properties was first to call for reduced engine oil volatility and later to progressively restrict the amount of phosphorus (and thus, ZDDP) that could be used in formulating engine oils.

3. PEI as a measure of ZDDP volatility in the engine 3 A new apparatus was developed which not only showed good correlation with Noack’s device and repeatability but in addition collected all volatile material produced in the 1-hr., 250° test. In the early 1990’s, the Savant Lab wanted to apply a well- known oil volatility test developed by K. Noack many years previously (in the 1930s) that was still considered an effective test for determining engine oil volatility. History (cont.) However, Noack’s use of the toxic low-melting amalgum of tin, bismuth, and lead called Woods Metal as a heat transfer material in heating the metal cup containing the test oil was not considered acceptable in the Savant Lab. The resulting instrument was relatively compact and simple to use …..

4. PEI as a measure of ZDDP volatility in the engine 4 Design principles of instrument Temperature Sensor and Controller Test Oil Air Inlet Vacuum Monitor Noble Metal Heater & Insulation Volatiles Collection Vessel Reaction Flask Top & Bottom Vacuum Filter & Drain Temperature Sensor and Controller Test Oil Air Inlet Vacuum Monitor Noble Metal Heater & Insulation Volatiles Collection Vessel Reaction Flask Top & Bottom Vacuum Filter & Drain

5. PEI as a measure of ZDDP volatility in the engine 5 1. Is phosphorus volatility affected by engine oil volatility? Subsequent studies of engine oil’s volatile products showed that considerable phosphorus was also volatilized at 250°C. The answers were interestingly and even surprising …. Background of development of the PEI With the growing concern about ZDDP levels in engine oil, and the availability of the special volatiles-collecting Noack protocol, it was worthwhile to test some assumptions: 2. To what degree is phosphorus volatility affected by phosphorus concentration in the fresh engine oil?

6. PEI as a measure of ZDDP volatility in the engine 6 No correlation was found with percent oil volatilized:

7. PEI as a measure of ZDDP volatility in the engine 7 Little correlation existed with initial phosphorus concentration:

8. PEI as a measure of ZDDP volatility in the engine 8 Another view comparing initial and volatile phosphorus levels:

9. PEI as a measure of ZDDP volatility in the engine 9 Information generated somewhat later showed that this was, in fact, the case …… At the time it was suggested 1 that likely phosphorus volatility was related to differences in the decomposition mechanism of the phosphorus-containing additives as well as to the presence and influence of other additives in the formulated oil. To equivalently compare phosphorus volatility of all engine oils, the mass of phosphorus volatilized from the new Noack test was converted to mg/L of engine oil and this value was called the Phosphorus Emission Index. PEI = mg vol /L oil Background of development of the PEI 1 T.W. Selby, “Development and Significance of the Phosphorus Emission Index”, 13 th International Colloquium Tribology, Esslingen, Germany, 2002.

10. PEI as a measure of ZDDP volatility in the engine 10

11. PEI as a measure of ZDDP volatility in the engine 11 The PEI values obtained in a sequential study of five tests from 10 to 50 minutes was made at 250°C. The oils were identical except for the ZDDP composition which in one set was a primary and the other a secondary alcohol ZDDP 2. It was recognized that a combination of PEI and NMR could provide further understanding of the decomposition of ZDDPs in the environment of the automotive engine. It was interesting and technically helpful in assessing the discriminating ability of the PEI method that considerable differences were shown between ZDDPs made with primary and secondary alcohols. Cooperative Studies of PEI and NMR 2 T.W. Selby, R.J. Bosch, D.C. Fee, “Phosphorus Additive Chemistry and Its Effects on the Phosphorus Volatilization of Engine Oils”. Elemental Analysis of Fuels and Lubricants, Ed. Nadkarni, ASTM STP 1468, pp. 239-254,.

12. PEI as a measure of ZDDP volatility in the engine 12 Time and chemistry effects on PEI:

13. PEI as a measure of ZDDP volatility in the engine 13 Summarizing, these PEI studies at 250°C showed that: : 2. One ZDDP, made with a primary alcohol, continued to emit phosphorus over the 50-minute exposure period. The differences made it technically interesting and valuable to measure the NMR spectra on samples of the fresh, volatile, and residual samples from these PEI analyses. Cooperative Studies of PEI and NMR (cont.) 1. At the same concentration, with the same base stock and concentrations of other additives, two different ZDDPs showed considerably different responses. 3. ZDDP made with a secondary alcohol stopped producing volatile phosphorus within 10 minutes of exposure to the Noack protocol.

14. PEI as a measure of ZDDP volatility in the engine 14 NMR studies 3 confirmed the differences shown by PEI: Cooperative Studies of PEI and NMR (cont.) ZDDP with primary alcohol: 10-minute exposure Volatiles Original oil Residue oil Volatiles Original oil Residue oil 50-minute exposure 3 R.J. Bosch, et.al., “Analysis of the Volatiles Generated during the Selby- Noack Test by 31 P NMR Spectroscopy”, Elemental Analysis of Fuels and Lubricants, Ed. Nadkarni, ASTM STP 1468, pp. 255-273, 2005.

15. PEI as a measure of ZDDP volatility in the engine 15 Summarizing: the NMR studies of the primary alcohol containing ZDDP showed that: 3. At both the 10-minute and 50-minute exposures, some form of organic phosphorus-containing species remained in the residual oil. Cooperative Studies of PEI and NMR (cont.) 1. The 31 P spectra changed within the first 10 minutes but then became relatively stable in appearance up to 50 minutes. 2. Inorganic phosphates showed up on the spectra within 10 minutes and grew somewhat with exposure time as shown at 50-minutes. 4. Organic phosphorus continued to be available for volatilization over the 50-minutes of exposure to 250°C.

16. PEI as a measure of ZDDP volatility in the engine 16 Cooperative Studies of PEI and NMR (cont.) 10-minute exposure ZDDP with secondary alcohol: Residue oil Volatiles Original oil

17. PEI as a measure of ZDDP volatility in the engine 17 The NMR studies of the secondary ZDDP additive showed that: : 2. Within 10-minutes of exposure to the PEI protocol, none of the original ZDDP additive spectra remained in the residual oil and none was further available for further volatilizing as shown in the PEI data on the oil. Cooperative Studies of PEI and NMR (cont.) 1. The 31 P spectra changed within the first 10 minutes. 3. A comparatively large amount of inorganic phosphates showed up just above 0 on the spectra at 10 minutes and did not change with exposure time. The PEI and NMR work thus agreed and indicated that the PEI was a useful tool to help unravel phosphorus volatility.

18. PEI as a measure of ZDDP volatility in the engine 18 Another approach to determining phosphorus volatility was by measuring difference in phosphorus concentration of the engine oil before and after some given engine test period. This was interesting information and opened a study of PEI 165. Temperature Effects on PEI Recent Information generated by such an approach at very high operating engine oil temperatures (at or near 165°C) was said not to agree with PEI values of 250°C (PEI 250 ). Temperatures of 250°C at which the special Noack was normally run to generate PEI values (PEI 250 ) reflected reported upper-cylinder, ring-belt temperatures. A means of obtaining PEI 165 data was developed and first applied to four ILSAC GF-4 oils having relatively moderate PEI 250 values ….

19. PEI as a measure of ZDDP volatility in the engine 19 Temperature Effects on PEI (cont.) Comparative evaluation of PEI 250 and PEI 165 values:

20. PEI as a measure of ZDDP volatility in the engine 20 1. Phosphorus volatility and PEI decrease markedly with a significantly lower temperature. The data on Oils A, B, C, and D show that : This information led to the question of whether the mechanism for phosphorus volatilization changes at lower temperatures compared to higher temperatures. A recent paper presented the nuclear magnetic resonance (NMR) analyses of the fresh, volatilized, residual engine oil for Oils A, B, C, and D in the previous slide 4. 2. The effect of lower temperature on phosphorus volatility is different for different oils. 4 R.J. Bosch, et. al.. ”Continued Studies of the Causes of Engine Oil Phosphorus Volatility”, SAE Powertrain Meeting, San Antonio, Oct., 2005. Temperature Effects on PEI (cont.) These data are shown on the next slides …..

21. PEI as a measure of ZDDP volatility in the engine 21 NMR analysis of Oil A PEI 250 = 25 Volatile Oil Fresh Oil Residue Oil Transformed phosphorus From To Inorganic phosphorus To Temperature Effects on PEI and NMR

22. PEI as a measure of ZDDP volatility in the engine 22 NMR analysis of Oil A PEI 165 = 4 Volatile Oil Fresh Oil Residue Oil Transformed phosphorus From To No inorganic phosphorus Temperature Effects on PEI and NMR

23. PEI as a measure of ZDDP volatility in the engine 23 Residue Oil NMR analysis of Oil B PEI 250 = 20 Volatile Oil Fresh Oil Transformed phosphorus From To Much inorganic phosphorus To None left Temperature Effects on PEI and NMR

24. PEI as a measure of ZDDP volatility in the engine 24 NMR analysis of Oil B PEI 165 = 3 Volatile Oil Fresh Oil Residue Oil Untransformed phosphorus Same Same? Same No inorganic phosphorus Temperature Effects on PEI and NMR

25. PEI as a measure of ZDDP volatility in the engine 25 NMR analysis of Oil C PEI 250 = 8 Volatile Oil Fresh Oil Residue Oil Transformed phosphorus From To None left Inorganic phosphorus To Temperature Effects on PEI and NMR

26. PEI as a measure of ZDDP volatility in the engine 26 NMR analysis of Oil C PEI 165 = 2 Volatile Oil Fresh Oil Residue Oil Untransformed phosphorus Same? Same No inorganic phosphorus Same Temperature Effects on PEI and NMR

27. PEI as a measure of ZDDP volatility in the engine 27 NMR analysis of Oil D PEI 250 = 13 Volatile Oil Fresh Oil Residue Oil Transformed phosphorus From To Inorganic phosphorus To None left To Temperature Effects on PEI and NMR

28. PEI as a measure of ZDDP volatility in the engine 28 NMR analysis of Oil D PEI 165 = 1 Volatile Oil Fresh Oil Residue Oil Untransformed phosphorus Same Very little Same No inorganic phosphorus Temperature Effects on PEI and NMR

29. PEI as a measure of ZDDP volatility in the engine 29 2. The 165°C spectra show no formation of inorganic phosphates so evident in the NMR spectra at 250°C. 1. There is a marked change in the degree of susceptibility to decomposition among these four oils when the exposure temperature is reduced. The data in these previous slides show that : Since oils A, B, C, and D had relatively moderate levels of PEI 250 and raised the question of what response would be generated by oils with much higher levels of PEI 250. ….. 3. The residuals of Oils B, C, and D show no significant change in the chemistry of their ZDDPs at 165°C. Temperature Effects on PEI and NMR 4. However, Oil A does show change at 165°C and also retains some of its organic phosphorus at 250°C in much the same manner as the previous primary alcohol ZDDP.

30. PEI as a measure of ZDDP volatility in the engine 30 Five engine oils were provided from a selection of the Institute of Materials (IOM) Engine Oil Database for PEI 165 analyses. PEI 250 values ranged from 56 to 95 which placed all five among the 100 th percentile of highest phosphorus volatility. The following graph compares their PEI 165 and PEI 250 ….. All of the oils were from North America. Phosphorus concentrations in the fresh oils ranged from 780 to 1520 PPM. Temperature Effects on PEI

31. PEI as a measure of ZDDP volatility in the engine 31 Temperature Effects on PEI (cont.)

32. PEI as a measure of ZDDP volatility in the engine 32 The data in the last graph show that the difference between PEI 165 and PEI 250 may be large and phosphorus volatility must rise significantly between such different values. Oils 1 and 3 – with initial phosphorus levels of 780 and 839 PPM – were chosen for the study. It was considered interesting and relevant to determine the effect of temperature on PEI between 165° and 250°C. Both Oils 1 and 3 were classified as SAE 10W-30 but only Oil 1, was indicated to carry both the API ‘Doughnut’ and ILSAC ‘Starburst’ symbols. Temperature Effects on PEI (cont.)

33. PEI as a measure of ZDDP volatility in the engine 33 PEI T values were obtained at temperatures of 190°, 215°, and 230°C to give the following results: Temperature Effects on PEI 250 (cont.)

34. PEI as a measure of ZDDP volatility in the engine 34 A similar study of Oils C and D, the two GF-4 oils made by the same company from different locations in North America. Results are plotted on the previous graph ….. It is evident that phosphorus volatility changes markedly with temperature for oils having large differences in one- hour PEI values determined between 165° and 250°C. Considering the previous NMR data, it would also be expected that the chemistry of the ZDDPs also changes between these temperatures. Temperature Effects on PEI 250 (cont.)

35. PEI as a measure of ZDDP volatility in the engine 35 Again, PEI T values were obtained at additional temperatures of 190°, 215°, and 230°C to give the following results: Temperature Effects on PEI 250 (cont.)

36. PEI as a measure of ZDDP volatility in the engine 36 The temperature effect on PEI of engine oils also led to the question of what effect on PEI might be observed with longer exposure of a sample. Oils 1 and 3 were chosen for this study over exposure periods of 1, 2, 6, 16, and 24 hours ….. The change in volatility with temperature is, as expected, more moderate and even seems to show small peaks at about 230°C (although this may be experimental error). Temperature and Exposure Time Effects on PEI

37. PEI as a measure of ZDDP volatility in the engine 37 Exposure Time Effects on PEI 165

38. PEI as a measure of ZDDP volatility in the engine 38 The data from these two oils having high PEI 250 values show surprisingly responsive phosphorus volatility over time when exposured at 165°C. Considering that there is a finite amount of ZDDP in a formulation, such an exponential response brought the question of what longer exposure time might produce. Accordingly, a 48-hour study was made of both oils to determine their PEI 165 values ….. Phosphorus volatility is found to increase exponentially with increasing exposure time over the 24-hour period with the PEI 165 values approaching the 1-hr. PEI 250 value. Exposure Time Effects on PEI 165 (cont.)

39. PEI as a measure of ZDDP volatility in the engine 39 Exposure Time Effects on PEI 165 (cont.)

40. PEI as a measure of ZDDP volatility in the engine 40 Analyzing the data to determine the rate of change of PEI 165 with time of exposure …. Exposure Effects on PEI 165 (cont.)

41. PEI as a measure of ZDDP volatility in the engine 41 PEI 165 is first found to increase markedly with exposure time up to 24 hours and then by 48 hours show tendency to reach a plateau at a fairly high rate of phosphorus volatility. On the basis of this data, It is not surprising that, in regard to the amount of phosphorus volatized at 48 hours, PEI 165, can be much greater than PEI 250. Exposure Effects on PEI 165 (cont.) This behavior is clearly contrary to that found in determining PEI 250 in the first studies discussed earlier. Such response indicates that at 165°C there is a continuing process of phosphorus volatilization when phosphorus does not quickly form inorganic phosphates as at 250°C. The mass of volatile phosphorus collected in 48 hours is about 1% of the phosphorus that may be available for volatilization.

42. PEI as a measure of ZDDP volatility in the engine 42 GF-4 Oils C and D – oils that had considerably lower values of PEI 250 than Oils 1 and 3 – were used for further studies. Comparative Temperature Effects on PEI On the basis of the exposure-time study at 165°C, 16 hours exposure was chosen as an appropriate temperature for further work at temperatures lower than 200°C. PEI T evaluations were first conducted at normal operating temperatures – 1. PEI 250 representing ring-belt/upper cylinder wall area. 2. PEI 120 representing higher, but not uncommon, engine oil temperatures. 3. PEI 140 representing considerably higher, less common, engine oil temperatures.

43. PEI as a measure of ZDDP volatility in the engine 43 Comparative Temperature Effects on PEI (cont.)

44. PEI as a measure of ZDDP volatility in the engine 44 The graph shows that at normal or somewhat higher operating temperatures, most of the phosphorus volatility for these two oils is generated at PEI 250 the ring-belt/upper-cylinder area. With the interesting data obtained in the studies of PEI 165 shown previously that represent uncommon and onerous engine operating temperatures, it was of significance to determine these values for comparison ….. The data also show that Oil C has somewhat lower PEI T values than Oil D at all three temperatures. Comparative Temperature Effects on PEI (cont.)

45. PEI as a measure of ZDDP volatility in the engine 45 Comparative Temperature Effects on PEI (cont.)

46. PEI as a measure of ZDDP volatility in the engine 46 This graph shows that at very high operating temperatures – similar to some engines tests such as IIIG – the phosphorus volatility shown by PEI 165 for these two oils is much greater than any normal operating temperature source. Considering the significance of this data and the question of correlation of the PEI with phosphorus deposits on the exhaust catalyst, it was of significance to measure the PEI 165 values at 16 hours of exposure for the three taxi fleet oils – RO-132, RO-133, and RO-136 – that had shown correlation with PEI 250 early in the study of the PEI protocol ….. Comparative Temperature Effects on PEI (cont.)

47. PEI as a measure of ZDDP volatility in the engine 47

48. PEI as a measure of ZDDP volatility in the engine 48 Comparative Temperature Effects on PEI (cont.) The data suggest that PEI 250 data correlates with taxi data because of ring-belt temperatures are the phosphorus source.

49. PEI as a measure of ZDDP volatility in the engine 49 The study of the three taxi oils confirmed predictions made in the development of the PEI concept and the tests of prior assumptions of oil volatility and phosphorus levels in fresh oil. Relationship between PEI and Calcium Additives Further, more recent evidence has been offered showing that calcium concentrations can modify the volatility of phosphorus. Such formulation expertise is a further valuable tool in the reduction of phosphorus emissions. However, this is a matter of astute formulation and not a statement that phosphorus emissions are solely dependent on calcium content – ZDDP chemistry also plays a role …..

50. PEI as a measure of ZDDP volatility in the engine 50 This is shown by analysis of the IOM database on engine oils. Relationship between PEI and Calcium Additives

51. PEI as a measure of ZDDP volatility in the engine 51 Technical development and selection of the additives for an engine oil have been very important to the lubrication of increasingly efficient and demanding engines. Observations Of these additives, ZDDPs are arguably the most critical component in today’s engine lubricants. Controlling engine oil volatility to control phosphorus volatility has been shown essentially meaningless. Phosphorus – present in all ZDDPs – has been shown to be a marked source of exhaust catalyst poisoning. This brought the dilemma of controlling the adverse effects of an important and universally used additive.

52. PEI as a measure of ZDDP volatility in the engine 52 (Note: this does not mean that increasing or decreasing ZDDP with no other formulation change would not have correlation.) Observations (cont.) Engine oil phosphorus volatility can best be – and perhaps only be – controlled by simple and dependable measurement of engine oil phosphorus volatility. Efforts to control phosphorus volatility by reducing concentration of phosphorus in the fresh oil also showed poor correlation. The critical issue is that trying to control phosphorus volatility effects by controlling initial phosphorus concentrations is not effective and, in some cases, is highly contradictory. High values of phosphorus emissions can come from very low levels of initial phosphorus concentrations and vice-versa.

53. PEI as a measure of ZDDP volatility in the engine 53 Observations (cont.) Correlation between PEI and NMR in regard to ZDDP decomposition are mutually supportive. NMR studies of fresh, volatilized, and residue samples from PEI have shown that phosphorus volatilization at ring belt temperatures quickly produces phosphorus volatiles and inorganic phosphates. At very high engine operating temperatures, PEI data indicates that phosphorus volatility from the circulating engine oil is high, continuous, and strongly time dependent. At normal to somewhat higher operating temperatures phosphorus volatility from the circulating engine oil is low. There are important implications of these latter observations.

54. PEI as a measure of ZDDP volatility in the engine 54 Observations (cont.) Lower temperature engine tests may have less variability in the phosphorus volatility generated but more variability in the temperature effects on ZDDP decomposition modes. As a repeatable bench test, the PEI T approach has significant advantages in the evaluation of engine oil phosphorus volatility in simplicity, flexibility, relativity to the problem and rapidity of application. Trying to indirectly determine phosphorus volatility using high temperature engine tests – 150°C and above – by extracting changes in phosphorus concentration is a questionable and very time-consuming route because of the low level of repeatability, reproducibility, cost, and time anticipated.

55. PEI as a measure of ZDDP volatility in the engine 55 If there is technical interest in using the PEI protocol, the following are recommendations: Recommendations 2. With this threshold, initial phosphorus concentration levels presently specified should be relaxed to permit higher levels when the actual levels of volatilized phosphorus are shown to be significantly better than required. 3. To meet the 2007 time-line, an ASTM D02 task force could be quickly organized in June 2006 and a round robin started with oils already identified as producing certain levels of catalyst deposits. 1. Fresh engine oils tests be conducted at PEI 250 and some other PEI T – the latter exposure for 16 hours. Acceptable limits could be simply chosen or established on the basis of correlation with phosphorus on the exhaust catalyst.

56. PEI as a measure of ZDDP volatility in the engine 56 Thanks very much for your patience! Question time?