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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.

The technology has been developed which will allow manufacturers to produce cars capable of running on methanol/gasoline blends with a methanol content up to 85% (i.e., M85). These cars will operate on varying methanol/gasoline ratios without any adjustments from the driver. The dual-fuel capability is attractive since vehicle use will not be handicapped by a restricted fuel distribution system. In addition, it provides the option of running on an environmentally “cleaner” fuel where it is available. The advent of fuel-flexible vehicles encourages the development of lubricants which will satisfy the demands of both fuels. The unique properties of methanol, however, increase the challenges of meeting the lubricant performance needs. Field and engine dynamometer testing have been aimed at understanding the response of key lubricant variables with M85. Short-trip, cold-weather conditions have been of particular concern.

Emissions system durability may be influenced by many engine oil formulation variables. Previous studies have suggested that emissions system durability is optimized by high metal/phosphorus ratios. Reducing the level of phosphorus in the engine oils has also been suggested as a means of prolonging the efficiency of the catalytic converter. This paper explores engine oil formulation variables which may influence the efficiency of the emissions system. Phosphorus type and amount are examined as potential catalytic deactivators, as well as detergent metal interactions with the phosphorus. Dynamometer and over-the-road test data are presented which suggest that the volatility characteristics of the phosphorus component in the engine oil may influence the degree of catalyst contamination. To explore fully the many variables, however, will require an emissions performance test.

Viscosity Modifiers (VM's) are commonly sold as polymer in oil concentrates. Thus, the handling (pumpability and mixability) characteristics of these systems are important practical considerations. These VM's normally are characterized only by kinematic viscosity, although they are handled at a range of shear rates/stresses which kinematic viscosity does not describe. New polymer types and structures and the desire to make the modifier level as high as possible requires more than a single point kinematic viscosity measurement. The rheological behavior of the concentrate is required to make economical systems that can be handled in a practical manner. This paper represents an initial study of viscosity modifier concentrates by rheological techniques.

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.

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.

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.

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.

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.

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.

This paper provides an overview of gear lubrication related to automotive equipment. A brief background in various aspects of lubrication, including lubrication theory, lubricant evaluation, performance designations, and formulation technology, is presented. This information is designed to assist those involved in the selection of automotive gear lubricants.

The authors provide evidence indicating that oils meeting only the minimum requirements of API GL-5 do not always provide adequate gear protection, especially in severe duty applications. Increases in commercial vehicle power and loading have accentuated the need for oils of greater load carrying ability. A modified version of the standard L-37 test may help identify oils that possess superior durability and thermal characteristics. Future gear lubricants should provide improved fuel economy, increased manual transmission life; and frictional characteristics that allow noise free performance in limited slip differentials.

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.

Classical journal bearing equations predict the function of oil flow in dissipating heat, thereby governing the effective viscosity of the lubricant in bearings. From this perspective, experimental dynamometer tests explored low speed, high load, high temperature, operation of four low viscosity oils. Test length was 48 hours using a 3.8L V-6 engine under steady state and cyclic conditions. With a 1.4 cP HTHSR viscosity oil the bearing distress appeared dependent on connecting rod bearing clearances serving to govern rate of oil flow through the main bearings. Front and rear main bearings exhibited severe overheat-distress. This was related to the design of the oil distribution system in the crankshaft. A severe cyclic acceleration test showed little bearing distress. Significant distress occurred only with an SAE 5W viscosity grade. SAE 5W-30 and 5W-40 multigrades showed no abnormal wear. Results were interpreted in terms of high temperature, high shear rate rheology of the test oils.

A major drive to develop methanol-fueled vehicles began with the 1973 oil embargo. Early work with dedicated methanol-fueled vehicles demonstrated that lubricant choice influenced engine durability. The qualities desired were not defined by the gasoline engine oil classification system in place at the time. As a result oils were developed which optimized those properties deemed desirable for methanol fuel. The advent of fuel sensors made it possible to design a vehicle which can operate on gasoline or gasoline with varying levels of methanol without intervention by the operator. This created a need for a lubricant that can handle a diversity of methanol/gasoline mixtures as well as conventional gasoline. The paper reviews some of the lubricants that have been used in prototype methanol-capable vehicles and the improvement of these formulations to meet the latest gasoline engine performance criteria while maintaining satisfactory methanol performance.

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.

In the first paper in this series (1)*, the extent of oil thickening for a given lubricant in the Mack T-7 engine test was found to be influenced by fuel composition. Based upon the knowledge that thickening is due to the accumulation and aggregation of soot in the oil, a set of experiments has been carried out to identify relationships between fuel chemistry and the oil thickening tendency of soot formed by fuel combustion. Three commercial diesel fuels were treated with chemical combustion aids and/or organic sulfur, and both short-duration and full-length tests were run in a Mack T-7 engine fitted with a filter designed to collect soot from the exhaust stream. A model describing the complex effects of fuel chemistry on the oil thickening process is proposed in which fuel sulfur content is shown to influence soot content of the lubricant after ISO hours of engine operation.

For a diesel lubricant to meet the new Mack EO-K/2 specification, it must be effective in preventing excessive viscosity increase during the 150-hour Mack T-7 test. The severity of this test is shown to be highly dependent upon fuel chemistry and injection timing. A comparison of various lubricant formulations in the Mack T-7 engine run with a given fuel suggests that nitrogen-containing succinimide dispersants, dispersant viscosity improvers, and supplemental ash in the form of overbased sulfonate detergents are effective in controlling viscosity increase. Crankcase oil thickening follows a modified form of Brinkman’s equation and can be predicted from measured values of soot particle size and concentration. Basic lubricant additives are shown to prevent particle size growth by adsorption on to the acidic soot surface, thereby interrupting soot aggregation and retarding oil thickening.

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.