This is about diesel engines but still interesting. http://www.astmtmc.cmu.edu/docs/diesel/hdeocp/minutes/2001/hdeocp.2001-06/0601ATT18.PDF
http://www.sae.org/technical/papers/980702
Quote:
Properties of engine bearings were investigated with different bearing materials and different HTHS viscosity oils by means of both an engine test and a rig test.
The rig test well simulated the bearing wear which occurred in the engine test. Lead-bronze bearings with lead-tin-indium overlay gave the least amount of wear in operating under high-speed and heavy-load conditions even with low HTHS viscosi Aluminum bearings without overlay gave good wear resistance in the case of no seizure occurrence. The wear amount of bearings were well correlated with HTHS viscosity, not with kinematic viscosity.
http://www.sae.org/technical/papers/922342
Quote:
Two programs were conducted to study the relationships between engine oil rheology and crankshaft bearing wear. A chassis dynamometer test of four oils in four cars was used to explore and define the key variables affecting bearing wear. There results were used to design a field test of nine oils in 45 taxicabs in New York City. The test oils (SAE 0W-20 to 20W-20) were formulated to measure the effects of viscosity, viscosity index improver, and detergent inhibitor package. Bearing wear tended to be either low and unremarkable or very high, particularly in the thrust bearings. Oil performance was best expressed as the frequency of excessive wear, rather than by quantitative wear measurement. There were many instances of very high wear in cabs operated with the lowest viscosity oils but none in cabs with higher viscosity oils. Non-Newtonian oils appeared to provide slightly more protection than Newtonian oils of the same HTHS viscosity, and a higher quality adpack also appeared to provide benefits. However, these factors were secondary to the viscosity of the oil. HTHS viscosity was a better predictor of beairng wear performance than oil film thickness.
Here is a way of getting better fuel economy in the API Sequence VIB engine test.
http://www.freepatentsonline.com/WO2008005100.html
Quote:
The high temperature high shear (HTHS) data was measured using a fully formulated 5w30 weight crankcase engine oil formulation; however, different viscosity index modifier polymers were employed to demonstrate their contribution. The HTHS of an oil is determined according to ASTM D5481 using a capillary tube. This evaluates the oil at an elevated temperature and shear rate to better attempt to simulate actual extreme engine operating conditions. This replaces the Minimum. Oil Film Thickness (MOFT), MOFT data from operating engines generally has not provided a good correlation with actual wear in service. [0068] Fuel economy has been measured by the American Petroleum Institute's Sequence VIB engine test (ASTM D6837) which measures fuel economy improvement (% FEI) of a formulated engine oil and consists of several stages in which the oil temperature ranges in temperature from 45 0 C to 125° C. In more than half of the time during the Seq. VIB test in which the %FEI is measured, the oil temperature is held at 70 0 C or lower.
[0069] Viscosity Index Improver polymers which show distinct reductions in HTHS at the temperatures encountered in the Sequence VIB test are believed to increase the measured % FEI (Fuel Economy Improvement) of an oil. A good indication of the potential of a Viscosity Index Improver polymer to improve fuel economy is therefore provided by looking at the HTHS behaviors of the polymer at temperatures at about 70 0 C or lower. Thus, one aspect of the present invention is directed to a method for improving the fuel economy of a engine oil comprising selecting a plurality of viscosity index improver polymers, screening the polymers at HTHS at temperatures at about 7O 0 C or lower and optionally at a plurality of temperatures, evaluating the HTHS results, and selecting a polymer candidate. The preset temperatures of 50 0 C and 75°C for the Cannon Series I High Temperature High Shear Capillary Viscometer are therefore convenient for investigating fuel economy. A good way to get an indication of the potential for fuel economy improvement is to compare the HTHS of one polymer against another polymer, for example a commercial polymer or other reference polymer. Since some polymers might be expected to have lower HTHS at different temperatures, a good assessment of the overall fuel economy performance is to measure and calculate the difference between the HTHS of a polymer and the
reference polymer at both 50 0 C and 75°C. A Fuel Economy Index (FEI) can then be calculated as adding the differences in HTHS measured at the two temperatures:
FEI = (HTHS rφrence - HTHS polymer \^ + {HTHS reβrence - HTHS polymer \ sec
[0070] A high value of FEI calculated in this way, for example greater than 3.0, indicates a polymer which generally has a substantially lower HTHS viscosity at temperatures important to the Seq. VIB fuel economy engine test and therefore better fuel economy. The successful candidate can thereafter be blended to a formulated engine oil thereby improving the %FEI as measured in the Seq. VIB test.
http://www.sae.org/technical/papers/980702
Quote:
Properties of engine bearings were investigated with different bearing materials and different HTHS viscosity oils by means of both an engine test and a rig test.
The rig test well simulated the bearing wear which occurred in the engine test. Lead-bronze bearings with lead-tin-indium overlay gave the least amount of wear in operating under high-speed and heavy-load conditions even with low HTHS viscosi Aluminum bearings without overlay gave good wear resistance in the case of no seizure occurrence. The wear amount of bearings were well correlated with HTHS viscosity, not with kinematic viscosity.
http://www.sae.org/technical/papers/922342
Quote:
Two programs were conducted to study the relationships between engine oil rheology and crankshaft bearing wear. A chassis dynamometer test of four oils in four cars was used to explore and define the key variables affecting bearing wear. There results were used to design a field test of nine oils in 45 taxicabs in New York City. The test oils (SAE 0W-20 to 20W-20) were formulated to measure the effects of viscosity, viscosity index improver, and detergent inhibitor package. Bearing wear tended to be either low and unremarkable or very high, particularly in the thrust bearings. Oil performance was best expressed as the frequency of excessive wear, rather than by quantitative wear measurement. There were many instances of very high wear in cabs operated with the lowest viscosity oils but none in cabs with higher viscosity oils. Non-Newtonian oils appeared to provide slightly more protection than Newtonian oils of the same HTHS viscosity, and a higher quality adpack also appeared to provide benefits. However, these factors were secondary to the viscosity of the oil. HTHS viscosity was a better predictor of beairng wear performance than oil film thickness.
Here is a way of getting better fuel economy in the API Sequence VIB engine test.
http://www.freepatentsonline.com/WO2008005100.html
Quote:
The high temperature high shear (HTHS) data was measured using a fully formulated 5w30 weight crankcase engine oil formulation; however, different viscosity index modifier polymers were employed to demonstrate their contribution. The HTHS of an oil is determined according to ASTM D5481 using a capillary tube. This evaluates the oil at an elevated temperature and shear rate to better attempt to simulate actual extreme engine operating conditions. This replaces the Minimum. Oil Film Thickness (MOFT), MOFT data from operating engines generally has not provided a good correlation with actual wear in service. [0068] Fuel economy has been measured by the American Petroleum Institute's Sequence VIB engine test (ASTM D6837) which measures fuel economy improvement (% FEI) of a formulated engine oil and consists of several stages in which the oil temperature ranges in temperature from 45 0 C to 125° C. In more than half of the time during the Seq. VIB test in which the %FEI is measured, the oil temperature is held at 70 0 C or lower.
[0069] Viscosity Index Improver polymers which show distinct reductions in HTHS at the temperatures encountered in the Sequence VIB test are believed to increase the measured % FEI (Fuel Economy Improvement) of an oil. A good indication of the potential of a Viscosity Index Improver polymer to improve fuel economy is therefore provided by looking at the HTHS behaviors of the polymer at temperatures at about 70 0 C or lower. Thus, one aspect of the present invention is directed to a method for improving the fuel economy of a engine oil comprising selecting a plurality of viscosity index improver polymers, screening the polymers at HTHS at temperatures at about 7O 0 C or lower and optionally at a plurality of temperatures, evaluating the HTHS results, and selecting a polymer candidate. The preset temperatures of 50 0 C and 75°C for the Cannon Series I High Temperature High Shear Capillary Viscometer are therefore convenient for investigating fuel economy. A good way to get an indication of the potential for fuel economy improvement is to compare the HTHS of one polymer against another polymer, for example a commercial polymer or other reference polymer. Since some polymers might be expected to have lower HTHS at different temperatures, a good assessment of the overall fuel economy performance is to measure and calculate the difference between the HTHS of a polymer and the
reference polymer at both 50 0 C and 75°C. A Fuel Economy Index (FEI) can then be calculated as adding the differences in HTHS measured at the two temperatures:
FEI = (HTHS rφrence - HTHS polymer \^ + {HTHS reβrence - HTHS polymer \ sec
[0070] A high value of FEI calculated in this way, for example greater than 3.0, indicates a polymer which generally has a substantially lower HTHS viscosity at temperatures important to the Seq. VIB fuel economy engine test and therefore better fuel economy. The successful candidate can thereafter be blended to a formulated engine oil thereby improving the %FEI as measured in the Seq. VIB test.
This doesn't even cover all of the aspects of VIIs and their effects.
