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This paper outlines the history and background of the NLGI (formerly known as the National Lubricating Grease Institute) lubricating grease specifications, GC-LB classification of Automotive Service Greases as well as details on the development of new requirements for their High-Performance Multiuse (HPM) grease certification program. The performance of commercial lubricating grease formulations through NLGI's Certification Mark using the GC-LB Classification system and the recently introduced HPM grease certification program will be discussed. These certification programs have provided an internationally recognized specification for lubricating grease and automotive manufacturers, users and consumers since 1989. Although originally conceived as a specification for greases for the re-lubrication of automotive chassis and wheel bearings, GC-LB is today recognized as a mark of quality for a variety of different applications.

In this work, a novel bearing test rig was used to evaluate the impact of oil viscoelasticity on friction torque and oil film thickness in a hydrodynamic journal bearing. The test rig used an electric motor to rotate a test journal, while a hydraulic actuator applied radial load to the connecting rod bearing. Lubrication of the journal bearing was accomplished via a series of axial and radial drillings in the test shaft and journal, replicating oil delivery in a conventional engine crankshaft. Journal bearing inserts from a commercial, medium duty diesel engine (Cummins ISB) were used. Oil film thickness was measured using high precision eddy current sensors. Oil film thickness measurements were taken at two locations, allowing for calculation of minimum oil film thickness. A high-precision, in-line torque meter was used to measure friction torque. Four test oils were prepared and evaluated.

In the last decade, numerous studies have been conducted to investigate the mechanism of Low Speed Pre-Ignition (LSPI) in Turbocharged Gasoline Direct Injection (TGDi) engines. According to technical reports, engine oil formulations can significantly influence the occurrence of LSPI particularly when higher levels of calcium-based additives are used, increasing the tendency for LSPI events to occur. While most of the studies conducted to date utilized engine tests, this paper evaluates the effect of engine oil formulations on LSPI under real-world driving conditions, so that not only the oil is naturally aged within an oil change interval, but also the vehicle is aged through total test distance of 160,000 km. Three engine oil formulations were prepared, and each tested in three vehicles leading to an identical fleet totaling nine vehicles, all of which were equipped with the same TGDi engine.

Increasingly stringent fuel economy and emissions regulations around the world have forced the further optimization of nearly all vehicle systems. Many technologies exist to improve fuel economy; however, only a smaller sub-set are commercially feasible due to the cost of implementation. One system that can provide a small but significant improvement in fuel economy is the lubrication system of an internal combustion engine. Benefits in fuel economy may be realized by the reduction of engine oil viscosity and the addition of friction modifying additives. In both cases, advanced engine oils allow for a reduction of engine friction. Because of differences in engine design and architecture, some engines respond more to changes in oil viscosity or friction modification than others. For example, an engine that is designed for an SAE 0W-16 oil may experience an increase in fuel economy if an SAE 0W-8 is used.

The growing need for improved fuel economy is a global challenge due to continuously tightening environmental regulations targeting lower CO2 emission levels via reduced fuel consumption in vehicles. In order to reach these fuel efficiency targets, it necessitates improvements in vehicle transmission hardware components by applying advanced technologies in design, materials and surface treatments etc., as well as matching lubricant formulations with appropriate additive chemistry. Axle lubricants have a considerable impact on fuel economy. More importantly, they can be tailored to deliver maximum operational efficiency over specific or wide ranges of operating conditions. The proper lubricant technology with well-balanced chemistries can simultaneously realize both fuel economy and hardware protection, which are perceived to have a trade-off relationship.

The operating conditions of a typical motorcycle are considerably different than those of a typical passenger car and thus require an oil capable of handling the unique demands. One primary difference, wet clutch lubrication, is already addressed by the current JASO four-stroke motorcycle engine oil specification (JASO T 903:2011). Another challenge for the oil is gear box lubrication, which may be addressed in part with the addition of a gear protection test in a future revision to the JASO specification. A third major difference between a motorcycle oil and passenger car oil is the more severe conditions an oil is subjected to within a motorcycle engine, due to higher temperatures, engine speeds and power densities. Scooters, utilizing a transmission not lubricated by the crankcase oil, also place higher demands on an engine oil, once again due to higher temperatures, engine speeds and power densities.

Wet clutch friction devices are the primary means by which torque is transmitted through many of today's modern vehicle drivelines. These devices are used in automatic transmissions, torque vectoring devices, active on-demand vehicle stability systems and torque biasing differentials. As discussed in a previous SAE paper ( 2006-01-3271 - Next Generation Torque Control Fluid Technology, Part II: Split-Mu Screen Test Development) a testing tool was developed to correlate to full-vehicle split-mu testing for limited slip differential applications using a low speed SAE #2 friction test rig. The SAE #2 Split-Mu Simulation is a full clutch pack component level friction test. The purpose of this test is to allow optimization of the friction material-lubricant hardware system in order to deliver consistent friction performance over the life of the vehicle.

Wet clutch friction devices are the primary means by which torque is transmitted in many of today's modern vehicle drivelines. These devices are used in automatic transmissions, torque vectoring devices, active on-demand vehicle stability systems, and torque biasing differentials. As discussed in a previous SAE paper ( 2006-01-3270 - Next Generation Torque Control Fluid Technology, Part I: Break-Away Friction Slip Screen Test Development), a testing tool was developed to simulate a limited slip differential break-away event using a Full Scale-Low Velocity Friction Apparatus (FS-LVFA). The purpose of this test was to investigate the fundamental interactions between lubricants and friction materials. The original break-away friction screen test, which used actual vehicle clutch plates and a single friction surface, proved a useful tool in screening new friction modifier technology.

Limited technical studies to speciate particulate matter (PM) emissions from gasoline fueled vehicles have indicated that the lubricating oil may play an important role. It is unclear, however, how this contribution changes with the condition of the lubricant over time. In this study, we hypothesize that the mileage accumulated on the lubricant will affect PM emissions, with a goal of identifying the point of lubricant mileage at which PM emissions are minimized or at least stabilized relative to fresh lubricant. This program tested two low-mileage Tier 2 gasoline vehicles at multiple lubricant mileage intervals ranging from zero to 5000 miles. The LA92 cycle was used for emissions testing. Non-oxygenated certification fuel and splash blended 10% and 20% ethanol blends were used as test fuels.

Life Cycle Assessment (LCA) is a methodology used to determine quantitatively the environmental impacts of a range of options. The environmental community has used LCA to study all of the impacts of a product over its life cycle. This analysis can help to prevent instances where a greater degree of environmental harm results when changes are made to products based on consideration of impacts in only part of the life cycle. This study applies the methodology to engine lubricants, and in particular chlorine limits in engine lubricant specifications. Concern that chlorine in lubricants might contribute to emissions from vehicle exhausts of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF), collectively called PCDD/F, led to the introduction of chlorine limits in lubricant specifications. No direct evidence was available linking chlorine in lubricants to PCDD/F formation, but precautionary principles were used to set lubricant chlorine limits.

Phosphorus is known to reduce effectiveness of the three-way catalysts (TWC) commonly used by automotive OEMs. This phenomenon is referred to as catalyst deactivation. The process occurs as zinc dialkyldithiophosphate (ZDDP) decomposes in an engine creating many phosphorus species, which eventually interact with the active sites of exhaust catalysts. This phosphorous comes from both oil consumption and volatilization. Novel low-volatility ZDDP is designed in such a way that the amounts of volatile phosphorus species are significantly reduced while their antiwear and antioxidant performances are maintained. A recent field trial conducted in New York City taxi cabs provided two sets of “aged” catalysts that had been exposed to GF-4-type formulations. The trial compared fluids formulated with conventional and low-volatility ZDDPs. Results of field test examination were reported in an earlier paper (1).

The popularity of SUVs and light trucks in North America, combined with the return to rear-wheel-drive cars globally, is significantly increasing the installation of torque control devices that improve vehicle stability and drivability. As with other driveline hardware, it is important to optimize the friction material-lubricant-hardware system to ensure that a torque control device provides consistent performance over the life of the vehicle. While there are many publications on friction tests relevant to automatic transmission fluids, the literature relating to torque control testing is not as well developed. In this paper, we will describe a split-mu vehicle test and the development of a split-mu screening test. The screening test uses the SAE#2 friction test rig and shows how results from this test align with those from actual vehicle testing.

The popularity of SUVs and light trucks in North America, combined with the return to rear-wheel-drive cars globally, is significantly increasing the installation rates of torque control devices that improve vehicle stability and drivability. As with other driveline hardware, it is important to optimize the friction material-lubricant-hardware system in order to ensure that a torque control device provides consistent performance over the life of the vehicle. While there are many publications on friction tests relevant to automatic transmission fluids, the literature relating to torque control testing is not as well developed. In this paper we will describe the development of a break-away friction screening test using a Full-Scale Low-Velocity Friction Apparatus (FS-LVFA). Additionally, we will illustrate how this screening test can be used to investigate the fundamental friction material-lubricant interactions that occur in continuously engaged limited slip differentials.

The popularity of light trucks and sport utility vehicles (SUVs), coupled with growing consumer demand for vehicles with more size, weight and horsepower, has increased the impact of these vehicle classes on the manufacturer's CAFE (Corporate Average Fuel Economy) numbers. Consumers often use light trucks and SUVs in applications such as prolonged towing at highway speeds, resulting in heavy loading and/or high operating temperatures in the axle. These conditions require superior axle lubricant protection, often provided by choosing a higher viscosity fluid (e.g., SAE 75W-140). Traditionally, the choice of these higher viscosity fluids for enhanced durability performance often results in reduced city-highway efficiency. This paper will describe the use of controlled axle dynamometer laboratory testing methods to develop fluids that maximize both fuel efficiency and durability performance across the wide spectrum of the new proposed viscosity classifications.

The popularity of light trucks and sport utility vehicles (SUVs), coupled with growing consumer demand for vehicles with more size, weight and horsepower, has challenged the original equipment manufacturers' (OEM) ability to meet the Corporate Average Fuel Economy (CAFE) specifications due to the increased contribution of these vehicle classes on fleet averages. The need for improved fuel economy is also a global issue due to the relationship of reduced fuel consumption to reduced CO2 emissions. Vehicle manufacturers are challenged to match the proper fluid with the application to provide the required durability protection while maximizing fuel efficiency. Recent new viscosity classifications outlined under SAE J306 aid in more tightly defining options for lubricant choice for a given application. Changes to the SAE J306 viscosity classification define new intermediate viscosity grades, SAE 110 and SAE 190.

The constant velocity joint (CVJ) has seen increased usage driven by the growth of front wheel drive vehicles over the last 30 years. The CVJ provides a smooth, dynamic connection between the output of the axle or gearbox and the driving wheels of the vehicle. The seemingly simple device, however, requires specially designed greases to maximize protection of the internal components from distress and provide optimum performance and service life. One measure of potential distress in the CVJ can be related to temperature rise which is a reflection of the friction and wear properties of the grease employed. A test rig was designed and a method created to evaluate the temperature response of different greases used in a CVJ. The test rig was designed to allow a wide range of speeds, torques and shaft angles to be used. The rig uses a unique temperature pickup system to allow for dynamic measurement of the grease temperature in the boot.

Consumer demand for size, weight and horsepower has dictated a prominent role for sport utility vehicles and light trucks in the product lines of major North American automobile manufacturers. Inherently less efficient than passenger cars, these vehicles will be facing more stringent light duty CAFE (Corporate Average Fuel Economy) standards beginning in 2005 when mileage targets will be elevated to 21 mpg; this figure will be further increased to 22.2 mpg by 2007. In order to accommodate both public demand and CAFE requirements, vehicle manufacturers are seeking ways to improve fuel economy through design and material modifications as well as through improvements in lubrication. The axle lubricant may have an important impact on fuel economy, and axle lubricants can be tailored to deliver higher levels of operating efficiency over a wide range of conditions.

The Sequence IIIG is a newly developed 100 hour test used to evaluate the performance of crankcase engine oils in the areas of high temperature viscosity increase, wear, deposits, pumpability, and ring sticking for the North American GF-4 standard. Data from the ASTM Precision Matrix, completed in the spring of 2003, along with early reference data from the Lubricant Test Monitoring System (LTMS) showed unexpected test results for selected oils and indicated that percent viscosity increase and pumpability were highly correlated with oil consumption. This correlation led to an intensive study of the factors that influence oil consumption and an attempt to compensate for non-oil related oil consumption through a model based adjustment of the results. The study and scrutiny of the IIIG data has led to more uniform oil consumption in the test and improved test precision, and has eliminated the need for a correction equation based on non-oil related oil consumption.

The Coordinating European Council, CEC, develops performance tests for the motor, oil, petroleum, additive and allied industries. In recent years, CEC has moved away from using round robin programmes (RRP's) for monitoring the precision and severity of test methods in favour of regular referencing within a test monitoring system (TMS). In a TMS, a reference sample of known performance, determined by cross-laboratory testing, is tested at regular intervals at each laboratory. The results are plotted on control charts and determine whether the installation is and continues to be fit to evaluate products. Results from all laboratories are collated and combined to monitor the general health of the test. The TMS approach offers considerable benefits in terms of detecting test problems and improving test quality. However, the effort required in collating data for statistical analysis is much greater, and there are technical difficulties in determining precision from TMS data.

The Lubricant Test Monitoring System (LTMS) is the calibration system methodology and protocol for North American engine oil and gear oil tests. This system, administered by the American Society for Testing Materials (ASTM) Test Monitoring Center (TMC) since 1992, has grown in scope from five gasoline engine tests to over two dozen gasoline, heavy duty diesel and gear oil tests ranging from several thousand dollars per test to almost one-hundred thousand dollars per test. LTMS utilizes Shewhart and Exponentially Weighted Moving Average (EWMA) control charts of reference oil data to assist in the decision making process on the calibration status of test stands and test laboratories. Equipment calibration is the backbone step necessary in the unbiased evaluation of candidate oils for oil quality specifications.