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Carefully controlled intake valve deposit (IVD) cleanup testing is found to be an effective method for differentiating the effect of the deposit control additives on combustion chamber deposits (CCD). The IVD buildup procedure produces a consistent initial level of CCD that the cleanup additive, the additive of interest, continues to build on until the end of the cleanup test. This “end of cleanup” CCD is found to be as repeatable and differentiable a measurement as tests run under the more common “keep clean” type operation. While IVD cleanup testing induces a mid-test disturbance in the form of the end of buildup measurement, it aligns well with two key CCD protocols in terms of the higher additive treat rates used and the extended total test length. In an analysis of results from IVD cleanup tests run using four different engine/vehicle procedures on seven different additives, several findings stood out.

Diesel fuel is a blend of various middle distillate components separated at the refinery. The composition and characteristics of the diesel fuel blend changes daily if not hourly because of normal process variation, changing refinery processing conditions, changing crude oil diet or changing diesel fuel and kerosene market conditions. Regardless of the situation going on at the refinery or the market, the resultant diesel fuel must consistently meet established cloud point specifications. To consistently meet the cloud point specifications, refiners are forced to blend their diesel fuels in such a way that the resultant blend is always on the low side of the cloud point specification even when the refining process adversely changes the fuel characteristics. This practice has the effect of producing several degrees of cloud point “giveaway” when the refinery is not experiencing adverse swings in product quality.

The major drivers in the development of the latest generation of engines are environmental. For diesel engines, mitigating the effects of soot contamination remains a significant factor in meeting these challenges. There is general consensus of soot impacting oil performance. Considerable efforts have been made towards a greater understanding of soot-lubricant interaction and its effects on engine performance. However, with evolution of engine designs resulting in changes to soot composition/ properties, the mechanisms of soot-lubricant interaction in the internal combustion engine continue to evolve. A variety of mechanisms have been proposed to explain soot-induced wear in engine components. Furthermore, wear is not the only topic among researchers. Studies have shown that soot contributes to oil degradation by increasing its viscosity leading to pumpability and lubricant breakdown issues.

The Association des Constructeurs Européen d'Automobiles (ACEA) light duty diesel engine specifications requires a kinematic viscosity measurement technique for Peugeot XUD-11 BTE drain oils. This viscosity measurement is used to define the medium temperature dispersivity of soot in the drain oil.(1) This paper discusses the use of rotational rheology methods to measure the Newtonian character of XUD-11 drain oils. The calculation of the rate index using the Hershel Bulkley model indicates the level of non-Newtonian behavior of the drain oil and directly reflects the level of soot dispersion or agglomeration. This study shows that the more non-Newtonian the drain oil the greater the difference between kinematic and rotational viscosity measurements Oscillation (dynamic) rheological techniques are used to characterize build up of soot structure.

One of the key functions of lubricating oil additives in diesel engines is to control oil thickening caused by soot accumulation. Over the last several years, it has become apparent that the composition of the base oil used within the lubricant plays an extremely important role in the oil thickening phenomenon. In particular, oil thickening observed in the Mack T-8 test is significantly affected by the aromatic content of the base oil. We have found that the Mack T-8 thickening phenomenon is associated with high electrical activity, i.e., engine drain oils which exhibit high levels of viscosity increase show significantly higher conductivities. These findings suggest that electrical interactions are involved in soot-induced oil thickening.

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.

Global emission legislations for diesel engines are becoming increasingly stringent. While the exhaust gas composition requirements for prior iterations of emission legislation could be met with improvements in the engine's combustion process, the next issue of European, North American and Japanese emission limits greater than 2005 will require more rigorous measures, mainly employment of exhaust gas aftertreatment systems. As a result, many American diesel OEMs are considering NOx adsorbers as a means to achieve 2007+ emission standards. Since the efficacy of a NOx adsorber over its lifetime is significantly affected by sulfur (“sulfur poisoning”), forthcoming reductions in diesel fuel sulfur (down to 15 ppm), have raised industry concerns regarding compatibility and possible poisoning effects of sulfur from the lubricant.

The world is firmly focused on reducing energy consumption and on increasingly stringent regulations on CO2 emissions. Examples of regulatory changes include the new United States Environmental Protection Agency's (U.S. EPA) fuel economy test procedures which were required beginning with the 2008 model year for vehicles sold in the US market. These test procedures include testing at higher speeds, more aggressive acceleration and deceleration, and hot-weather and cold-temperature testing. These revised procedures are intended to provide an estimate that more accurately reflects what consumers will experience under real world driving conditions. The U.S.

To investigate the effect of removing phosphorus lubricant additives from engine oil, a mileage accumulation programme was run using four 1.6 litre gasoline vehicles, two of which used phosphorus based lubricant oil additives, and the other two used boron based lubricant oil additives. The work showed that the catalyst systems deactivate during mileage accumulation, but emissions were still within the European Stage IV legislative limits at the completion of the mileage accumulation programme. Vehicles run with the boron oil show lower tailpipe emissions than the vehicles run with the phosphorus oil.

With the continued growth of the sport utility vehicle (SUV) market in North America in recent years more emphasis has been placed on fluid performance in these vehicles. In addition to fuel economy the key performance area sought by original equipment manufacturers (OEMs) in general has been temperature reduction in the axle. This is being driven by warranty claims that show that one of the causes of axle failure in these type vehicles is related to overheating. The overheating is, in turn, caused by high load situations, e.g., pulling a large trailer at or near the maximum rated load limit for the vehicle, especially when the vehicle or its main subcomponents are relatively new. The excessive temperature generally leads to premature failure of seals, bearings and gears. The choice of lubricant can have a significant effect on the peak and stabilized operating temperature under these extreme conditions.

The development of new transmission designs continues to affect the vehicle market. Continuously variable transmissions (CVTs) remain one of the more recent designs that impact the vehicle market. A desire for high belt-pulley capacity has driven studies concentrating on metal-on-metal (M/M) friction as a function of the CVT fluid. This paper describes the statistical techniques used to optimize the fluid friction as a function of additive components in a bench-scale, three-element test rig.

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.

Characteristics of E diesel, a fuel blend of diesel fuel and ethanol, are considered in a matrix of tests. One characteristic of particular concern and a subject of this investigation is that of stability. Methods to evaluate stability are looked at and compared in light of the potential for distillate and ethanol to separate under certain conditions. The quality of the fuel blend is enhanced by the use of enabling additives to ensure stability which necessitates development of a standard for assessment of the quality of stability. The properties of various base diesel fuels and their influence on stability are also studied. Other key characteristics are evaluated including viscosity, pour point, and oxidative stability.

SAE 2004-01-3009 reported on work conducted to investigate the correlation between the Mack T-11 laboratory engine tests and vehicle field tests. It concluded that the T-11 test provides an effective screening tool to investigate soot-related viscosity increase, and the severity of the engine test limits provides a substantial margin of safety compared to the field. This follow-up paper continues the studies on the 2003 Mack CV713 granite dump truck equipped with an AI-427 internal EGR engine and introduces experimentation on a 2003 CX613 tractor unit equipped with an AC-460P cooled EGR engine. The paper further assesses the correlation of the field trials to the Mack T-11 engine test and reviews the impact of ultra low sulfur diesel (ULSD) and prototype CJ-4 lubricant formulations in these engines.

Soot related viscosity increase has been reported as a field issue in some diesel engines and this led to the development of the T-11 engine test, incorporated in the Mack EO-N Premium Plus 03 specification (014 GS 12037). This study compares T-11 laboratory engine tests and vehicle field tests and seeks to confirm the correlation between them. The findings are that the T-11 test provides an effective screening tool to investigate soot related viscosity increase, and the severity of the engine test limits gives a substantial margin of safety compared to the field. A complementary study was conducted in conjunction with this work that focuses on the successful application of electrochemical sensor technology to diagnose soot content and soot related viscosity increase. This will be the subject of a separate paper.

Recently, research and testing of oxygenated diesel fuels has increased, particularly in the area of exhaust emissions. Included among the oxygenated diesel fuels are blends of diesel fuel with ethanol, or E diesel fuels. Exhaust emissions testing of E diesel fuel has been conducted by a variety of test laboratories under various conditions of engine type and operating conditions. This work reviews the existing public data from previous exhaust emissions testing on E diesel fuel and includes new testing performed in engines of varied design. Emissions data compares E diesel fuel with normal diesel fuel under conditions of different engine speeds, different engine loads and different engine designs. Variations in performance under these various conditions are observed and discussed with some potential explanations suggested.

Direct injection spark ignition (DISI) engine technology offers tremendous potential advantages in fuel savings and is likely to command a progressively increasing share of the European passenger vehicle market in the future. A concern is its propensity to form deposits on the inlet valve. In extreme cases, these deposits can lead to poor drivability and deteriorating emission performance. This inlet valve deposit build up is a well-known phenomenon in DISI engines since even additised fuel cannot wash over the back of intake valves to keep them clean. Two lubricants and two fuels were tested in a four car matrix. One of the lubricants was a fluid specifically developed by Lubrizol for DISI technology; the other was a baseline oil meeting Ford lubricants requirements and was qualified to ACEA A1/B1/ ILSAC GF2 performance level. Similarly, a baseline fuel was tested against an additised system.

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.

This paper features the results of emission tests conducted on diesel oxidation catalysts, and the combination of diesel oxidation catalysts and water blend fuel (diesel fuel continuous emulsion). Vehicle chassis emission tests were conducted using an urban bus. The paper reviews the impact and potential benefits of combining catalyst and water blend diesel fuel technologies to reduce exhaust emissions from diesel engines.

Soot is a typical byproduct of the diesel fuel combustion process, and a portion of the soot inevitably enters an engine's crankcase. A key functionality of a diesel engine lubricant is to disperse and suspend soot so that larger-particle agglomerations are prevented. The role of soot agglomeration in abrasive engine wear and lubricant viscosity increase is the subject of a continuing investigation; however, what is generally known is that once an engine lubricant loses its ability to control soot and a rapid viscosity increase begins, the lubricant has reached the end of its useful life and should be changed to maximize engine performance and life. This issue of soot related viscosity increase is of such importance that the Mack T-11 engine test was developed as a laboratory tool to evaluate lubricants. The newly proposed Mack EO-N Premium Plus - 03 specification includes a T-11 performance requirement.