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Advancement in Heavy Duty Diesel Engine Oils has, for approximately two decades, been driven by the ever more stringent emission legislation for NOx and Particulates. Over the last few years, the focus has shifted to reducing CO2 emissions, which created an interest in fuel efficient lubricants. In addition, increased fuel cost and a need to control operational expenses in a weaker economy have further heightened the interest in fuel efficient lubricants. Where the trucking industry was reluctant to move away from the tried and true SAE 15W-40 viscosity grade, there is now a strong interest in pushing the boundaries of lower viscosity to reduce internal friction in the engine and thereby improve fuel efficiency. Consequently, the industry is exploring and introducing lower viscosity grades, such as SAE 10W-30 and even SAE 5W-30.

New engine technologies are constantly being developed and introduced in order to meet increasing customer demands and government regulations. In many cases, improved engine oil performance is necessary to facilitate the implementation of new engine technologies. In order to meet increasing customer demands for performance, durability, and fuel economy, the engine builders are introducing hardware and operating cycles that place increasing demands on the engine oil. Each new North American Gasoline Engine Oil Performance Category has been developed with specific performance targets and improvements in mind. This paper will primarily focus on the initial steps in the development of engine oils for the GF-6 passenger car engine oil category in North America. GF-6 is scheduled to be introduced during the 1st quarter of 2015 and will supersede GF-5 and previous categories. It will also be backward compatible and will provide improved performance relative to GF-5 in many respects.

The heightened interest level in Fuel Economy for Heavy Duty Diesel Engines the industry has seen over the last few years continues to be high, and is not likely to change. Lowering the fuel consumption of all internal combustion engines remains a priority for years to come, driven by economic, legislative, and environmental reasons. While it is generally assumed that lower viscosity grade lubricants offer fuel economy benefits, there is a lot of confusion about exactly what drives the fuel economy benefits. Fuel Economy claims in trade literature vary over a broad range and it is difficult for the end user to determine what to expect when a change in lubricant viscosity is adopted for a fleet of vehicles in a certain type of operation. This publication makes an attempt at clarifying a number of these uncertainties with the help of additional engine test data, and more extensive data analysis.

Since the invention of the internal combustion engine, the contact between piston ring and cylinder liner has been a major concern for engine builders. The quality and durability of this contact has been linked to the life of the engine, its maintenance, and its exhaust gas and blowby emissions, but also to its factional properties and therefore fuel economy. While the basic design has not changed, many factors that affect the performance of the ring/liner contact have evolved and are still evolving. This paper provides an overview of observations related to the lubrication of the ring/liner contact.

The accumulation of ash in a Diesel Particulate Filter (DPF) eventually results in an increase in the pressure drop across the exhaust system component. This situation translates into a reduced capacity for soot, and requires an increased frequency of active regenerations to eliminate this soot. For heavy duty diesel applications, the lifetime of the DPF is long enough to expect that cleaning of the ash from the DPF will be required. The physico-chemical characteristics of the ash as a function of temperature and time will have an impact on the effectiveness of this cleaning. To develop a deeper understanding of this subject, four different samples of ash were characterized in this study that were collected under active or passive regeneration from exhaust systems of engines running on different fuels: ultra low sulfur diesel (ULSD), and biodiesel fuels B20 and B100. The lubricant, an API CJ-4 oil, was used for each engine test.

Partially Premixed Combustion (PPC) has shown its potential by combining high combustion controllability with emission characteristics that are close to those of an HCCI engine. In order to get PPC the ignition delay needs to be long enough for the fuel and air to mix prior to combustion. This can be achieved by injecting the fuel sufficiently early while running with high EGR. In order to find out where and how PPC occurs a map that shows the changes in combustion characteristics with injection timing and EGR was created. The combustion characteristics were studied in a six cylinder heavy duty engine where the Start of Injection (SOI) was swept from early to late injection over a wide range of EGR levels. The emissions were monitored during the sweeps and in the most promising regions, with low emissions and high efficiency, additional changes in injection pressure and engine speed were applied to get a more versatile picture of the combustion.

Fumigation was studied in a 12 L six-cylinder heavy-duty engine. Port-injected ethanol was ignited with a small amount of diesel injected into the cylinder. The setup left much freedom for influencing the combustion process, and the aim of this study was to find operation modes that result in a combustion resembling that of a homogeneous charge compression ignition (HCCI) engine with high efficiency and low NOx emissions. Igniting the ethanol-air mixture using direct-injected diesel has attractive properties compared to traditional HCCI operation where the ethanol is ignited by pressure alone. No preheating of the mixture is required, and the amount of diesel injected can be used to control the heat release rate. The two fuel injection systems provide a larger flexibility in extending the HCCI operating range to low and high loads. It was shown that cylinder-to-cylinder variations present a challenge for this type of combustion.

This paper describes mid-load experimental tests combining massive EGR rates and multiple injection strategies. Influence of very high EGR rates on combustion has been reviewed, and a response-surface-modeling tool has been used to present main results. Outputs from this empirical model did highlight a dramatic soot increase when oxygen concentration is reduced. The empirical model based on experimental results model was also used to define more precisely the EGR rate needed to reach US 2010 NOx target. This EGR rate being defined, some investigation has been made on dual-injection strategies combining a main injection with an early pilot injection. Both quantity and timing of pilot injection were varied, and experimental results showed large benefits of this strategy to reduce soot emissions without significant increase of NOx emissions or fuel consumption. Better results were also experienced with the addition of a close post-injection.

As on-highway, heavy-duty diesel engine designs have evolved to meet tighter emissions specifications and greater customer requirements, the crankcase environment for heavy-duty engine lubricants has changed. Engine lubricant quality is very important to help ensure engine durability, engine performance, and reduce maintenance downtime. Beginning in the late 1980's, a new Mack genuine oil specification and a new American Petroleum Institute (API) heavy-duty engine lubricant category have been introduced with each new U.S. heavy-duty, on-highway emissions specification. This paper documents the history and development of the Mack T-7, T-8, T-8A, T-8E, T-9, T-10, T-11, and T-12 engine lubricant tests.

Emission legislation for diesel engines is becoming more stringent over time. 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 emission limits may require more rigorous measures. In order to meet severe particulate matter limitations, such as those mandated in Japan's new long-term (2005-) emission regulation and in Euro-4 emission legislation, the use of exhaust gas after-treatment systems seems unavoidable. Many engine builders seem to have selected the Diesel Particulate Filter (DPF) as an integral part of their selected after-treatment strategy. It has been stated that engine lubricants may hurt the durability of such after-treatment systems when oil consumption results in deposit build-up on the DPF walls. This paper describes how a study was performed on the possible impact of engine lubricant composition on DPF plugging.