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Modern agriculture has evolved dramatically over the past half century. To be profitable, farms need to significantly increase their crop yields, and thus there are amplified demands on farming equipment. Equipment duty cycles have been raised in scope and duration, as the required output of the agricultural industry to sustain a growing population has stimulated the need for further advances in effective productivity gains on the farm. The mainstay mechanical assistant to the farmer, the tractor, has also evolved with the changes in modern agriculture to meet the requirements of these newer tasks. Larger, more capable vehicles have been introduced to help farmers efficiently meet these demands. At the same time, the current generation of tractor diesel engine lubricants has facilitated high levels of performance in the agricultural equipment market for many years. This is a testament to the role modern lubricants play in productivity in such a critical industry.

Gasoline direction injection (GDI) engines have been widely used by light-duty vehicle manufacturers in recent years to meet stringent fuel economy and emissions standards. Particulate Matter (PM) mass emissions from current GDI engines are primarily composed of soot particles or black carbon with a small fraction (15% to 20%) of semi-volatile hydrocarbons generated from unburned/partially burned fuel and lubricating oil. Between 2017 and 2025, PM mass emissions regulations in the USA are expected to become progressively more stringent going down from current level of 6 mg/mile to 1 mg/mile in 2025. As PM emissions are reduced through soot reduction, lubricating oil derived semi-volatile PM is expected to become a bigger fraction of total PM mass emissions.

Specific frictional properties are essential to provide correct and pleasurable shifting in a manual transmission. Synchroniser rings are being manufactured from an increasingly wider range of materials, and it is important to understand synchroniser-additive interactions in order to develop tailored lubricants that provide the desired frictional performance. This paper describes a study of the interaction of various friction modifier additives with a range of synchroniser materials in order to better understand the potential to develop lubricants that provide optimal frictional performance across a wide range of manual transmission-synchroniser systems.

This paper is part one of a longer term comparison of viscosity modifier behavior in modern automotive gear oil (AGO) fluids and the impact of these properties on fluid efficiency and durability. This first installment will compare the rheological properties, including EHD film thickness and traction coefficients, of the fluids across broad operating temperature, shear and load regimes and correlate these findings with rig efficiency testing. The effects of traction, EHD film thickness and high shear rheology on operating temperature are well documented and it is of particular interest to determine the extent to which different viscosity modifiers can beneficially impact these properties compared to a Brightstock-based SAE 80W90 grade fluid. The efficiency improvements of a VM would be for naught if it were not sufficiently shear stable and so comparisons are made between shear stable VM technologies.

Specific frictional properties are essential to provide correct and pleasurable shifting in a manual transmission. Synchroniser rings are being manufactured from an increasingly wider range of materials, and so it is important to understand synchroniser-additive interactions in order to develop tailored lubricants that provide the desired frictional performance. This paper describes a study of the interaction of various friction modifier additives with a range of synchroniser materials in order to better understand the potential to develop lubricants that provide optimal frictional performance across a wide range of manual transmission-synchroniser systems. This presentation will outline the results of testing fluids with a range of synchroniser materials and will be followed by a future paper that will describe details of the fluids and analysis of their interactions with the different synchroniser surfaces.

Requirements to reduce emissions and improve vehicle fuel economy continue to increase, spurred on by agreements such as the Kyoto Protocol. Lubricants can play a role in improving fuel economy, as evidenced by the rise in the number of engine oil specifications worldwide that require fuel economy improvements. A novel friction modifier technology has been developed to further improve vehicle fuel economy. The development of this novel friction modifier technology which contains only N,O,C,H was previously published along with the initial demonstration of performance in motorized Toyota engines. In order to validate this performance in fired engine tests, oil was evaluated in a Toyota Corolla Fielder with a 1500 cc gasoline engine. Testing was conducted in the Japanese 10-15 and JC08 modes, as well as the European EC mode, and the US FTP mode.

A discriminating dynamometer-based test was developed for evaluating cold start and warmup engine performance based on in-cylinder pressure measurements. The dynamometer test offers advantages in time required, flexibility and reduced variability over the vehicle procedure on which it was based. A parametric study on fuel driveability index (DI), ethanol content and intake valve deposit (IVD) rating demonstrated that each of these parameters had a statistically significant impact on engine cold start performance. Simple numerical offsets to fitted models based on oxygen content of the fuel did not account for the difference in engine performance of hydrocarbon-only versus ethanol-containing fuels. The effect of IVD on engine performance did not appear to depend on the DI of the fuel. The benefits of cleaner valves are seen even in fuels of very low DI.

The lubricant is a key component in the successful operation of a manual transmission, but it is important that the interactive effects with the friction material are understood. This paper examines the effect of several key additive components on the friction and wear performance of a single sinter composition in a carefully controlled laboratory test. In addition, the test method allows one to develop information about the shift behavior of the fluid-synchronizer material combination which provides useful information about shift quality. From the original experimental design program a predictive model was developed and an optimized formulation was tested as a validation of the results.

Extended drain of axle and transmission lubricants has gained wide acceptance in both passenger car and commercial vehicle applications. Understanding how the lubricant changes during extended drain operations is crucial in determining appropriate lubricants and drain intervals for these applications. A suitable aging screen test with an established relationship to field performance is essential. Over the years numerous methods have been studied (DKA, GFC, ISOT, ASTM L-60) with varying degrees of success1,2,3. Current methods tend to be overly severe in comparison to field experience, hence the need for further work in this area. As a result of recent work, a lubricant aging test method has been developed which shows good correlation with field experience, giving us an effective tool in the development of long drain oils.

The intent of industry and OEM factory fill oil specifications is to ensure lubricant pumping performance at low temperatures through rheological measurements using the Mini Rotary Viscometer and Scanning Brookfield tests. Often these tests provide conflicting information, yet lubricant formulations must be optimized to meet requirements of both tests. At the root of this issue is how test information is interpreted, since ultimately it is that interpretation that influences how specifications are set. In this paper, we focus on understanding the Scanning Brookfield test's gelation index which is part of ILSAC GF-2 and GF-3 specifications; our objective is to understand what is measured and its relation to meaningful low temperature lubricant performance. We approach this objective by measuring the low temperature rheology of mineral oils and lubricants formulated from these oils.

In API engine oil licensing, candidate oils must meet the performance requirements of category defined engine tests. While API category engine tests are developed to target a theoretical performance standard, it is rare that the cost to test and approve oils is understood. Given that engine tests are an integral part of oil evaluation, understanding of engine test value is necessary. Therefore, measurements of value are presented as Unbiased Engine Test Evaluation (UETE). UETE evaluates an engine test's draw on time and money resources by estimating the average number of tests required before a candidate oil will pass the category defined engine tests. A pilot study using the API CH-4 Category is presented.

Our basic understanding of the chemical and physical nature of soot, its interaction with lubricant components and its role in promoting wear and oil thickening in heavy duty diesel engines continues to grow. Our current study in the GM 6.5L engine focuses on examining the effects of variations in base stock type (Group I vs. Group II), viscosity index improver or viscosity modifier (VM) chemistry (OCP vs. dispersant OCP), zinc dithiophosphate (ZDP) type and dispersant type (low MW vs. high MW) on roller follower wear, viscosity growth and other measured responses. In this study, more robust fluids were tested producing very low wear results and minimal viscosity increase of the lubricant. Fluids containing dispersant OCP (DOCP) and high MW dispersant produced a lower degree of wear, whereas varying the ZDP type (1° vs. 2°) showed no effect on wear. The use of Group II base stocks was associated with significantly lower viscosity increases.

The international Lubricant Standardization and Approval Committee (ILSAC) GF-2 specification requires Passenger Car Motor Oils to provide enhanced fuel economy in a modern low friction engine (ASTM Sequence VIA). In previous SAE publications the authors have studied the boundary lubrication regime and documented the impact of friction modifiers and antiwear additives on Sequence VIA fuel economy. This paper shifts the focus to the hydrodynamic lubrication regime and details fundamental studies of viscosity modifiers and base oils on fuel economy as measured by this low friction engine. The viscosity modifiers were found to have surprisingly little impact on this test, while moving to base oils of higher viscosity index improved fuel economy as might be theoretically expected. A study of formulating SAE 5W-30 motor oils with base oils of increasing viscosity index showed the optimum fuel economy was able to be obtained with a high viscosity index base stock.

Despite the many years of widespread use of the BMW Intake Valve Deposit (IVD) vehicle test, relatively little has been published quantifying the variation in the test procedure. This paper presents an analysis of the variability in the BMW test. Though results from 8045 km (8K; 5,000 mile) tests rather than 16090 km (16K; 10,000 mile) are highlighted due to the size of the available database and relative sensitivity of the data, analysis suggests that variation at 8K is representative of 16K variation. A square root transformation of average deposit weight at 8K, though more cumbersome than the more common log transformation, is found to be the most appropriate way to eliminate the dependence of variation on the absolute level of deposits. Within-car variation is found to account for over half of the test-to-test variation, contradicting the notion that car-to-car differences are the dominant source of variability.

The International Lubricant Standardization and Approval Committee (ILSAC) GF-2 requirements for Passenger Car Motor Oils (PCMOs) will lower phosphorus limits from a maximum of 0.12% allowed by ILSAC GF-1 to a maximum of 0.10%. In effect, the ILSAC GF-2 phosphorus limit removes 17% of the most commonly used antiwear and antioxidant additive in current PCMOs, zinc dialkyldithiophosphate (ZDP). This paper outlines some work in ASTM Sequence V engine dynamometer tests to quantify the effect of reducing the ZDP on valve train wear and sludge formation. Engine data for the Sequence VE, the proposed Sequence VF, and the modified Sequence VE are presented. These three tests summarize the evolution of the Sequence V from the Sequence VE for GF-1 to the dual plug Sequence VE configuration for the GF-2 specification.

The proposed International Lubricant Standardization and Approval Committee (ILSAC) GF-2 specification requires Passenger Car Motor Oils to provide enhanced fuel economy in a modern low friction engine (Sequence VIA). This paper details fundamental studies of lubricant effects on fuel economy as measured by this low friction engine. Several conventional friction modifiers were tested with surprising results. One ester friction modifier, Ester B, which provides excellent fuel economy improvement in the Sequence VI, was found to be detrimental to the Sequence VIA. A second ester friction modifier, Ester A, performed as expected. Additionally, two molybdenum compounds, which are reported to provide excellent fuel economy in the Sequence VI, showed no fuel economy benefit in the Sequence VIA.

Statistically designed experiments were developed to investigate the nature of soot, to understand its role in oil viscosity growth, and to study the interactions involved with additives that inhibit viscosity growth. The matrix was designed to examine effects of engine type, mode of operation, and the oil formulations. Mack EM6-285 and GM 6.2L engines operating under both high speed and high torque conditions were used in this study. An API CE\SG quality lubricant was used as the baseline. The detergent sulfonate substrate was varied from standard to three-fold levels; the dispersant TBN contribution ranged from 1.1 to over 3.0. The surface and bulk exhaust soot properties were determined. Colloidal suspension stability and rheology were measured to evaluate the design factor effects on the formation of soot and subsequent effects on oil thickening. The Mack EM6-285 engine produced less soot, less oil viscosity growth, and less oxidation than the GM 6.2L engine.

Two prominent trends are facing diesel engine builders and their customers, environmental regulations and cost containment. Increasingly stringent exhaust emissions regulations have necessitated major changes in diesel engine design. Combustion temperatures and fuel injection pressures continue to rise. This and other factors, such as lower oil consumption for exhaust particulate reduction, place greater demands on crankcase lubricating oils. Another prominent environmentally related cost factor facing fleet operators is that of waste oil management. The inventory and disposal of used lubricants must now be handled in accordance with regulated guidelines and their associated costs. To compensate, new lubricant categories have been designed in both North America and Europe, such that 1994 and later emission controlled engines will perform as reliably as their earlier counterparts.

The effects of gasoline composition, as represented in typical regular and premium unleaded gasolines and fuel additives, on Combustion Chamber Deposits (CCD) were investigated in BMW and Ford tests. In addition, the influences of engine lubricant oil and ethanol oxygenate on CCD were examined in Ford 2.3L engine dynamometer tests. Also, additive effects of packages based on mineral oil fluidizers versus synthetic fluidizers were studied in several different engines for CCD. Finally, a new method for evaluating the effect of fluidizers on valve sticking is introduced.

Piston ring land deposit formation is a key performance criterion in the ASTM Sequence IIIE engine test. Because engine testing of lubricant formulation variables is expensive, a ring land deposit bench test was developed replicating the Sequence IIIE bulk oxidation and deposit formation mechanisms. Following an initial bulk oxidation of the candidate oils, deposits similar in chemical composition and morphology to Sequence IIIE ring land deposits are produced in a modified panel coker apparatus. Good correlation with the ASTM Sequence IIIE engine test has been established. Lubricant additive and base oil effects on oxidation control and deposit formation have been investigated. Their influences on lubricant formulation strategy are discussed.