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Technical Paper

A History of Mack Engine Lubricant Tests from 1985-2005: Mack T-7 through Mack T-12

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.
Technical Paper

A New CNG Engine Test for the Evaluation of Natural Gas Engine Oils

Compressed natural gas (CNG) has been used as a fuel for internal combustion engines for decades. CNG engines, in most cases, have been used in stationary applications for power generation, and pipeline gas transportation. More recently, CNG has found its way into mobile applications. Locally operating fleets, such as city bus fleets, have shown a lot of interest in CNG. Bus fleets operate most of the time in urban areas, where lower emission levels are mandated, and the operation allows the busses to return to a central refueling station on a daily basis. CNG engines are different from diesel engines in terms of lubricant requirements. Higher operating temperatures may require better oxidation and nitration control, and high ash levels can be a detriment. With the increased use of CNG as a fuel for commercial vehicle engines, it becomes more and more important to have a procedure to evaluate lubricants for this application.
Technical Paper

A New Engine Test for the Development of Heavy Duty Diesel Engine Oils for Engines with Exhaust Gas Recirculation: The Mack T-10 Test

More stringent emission legislation has been a driver for changes in the design of Heavy Duty Diesel engines since the 1980s. Optimization of the combustion processes has lead to significant reductions of exhaust emission levels over the years. However, in the year 2002, diesel engines in the USA will have to meet an even more stringent set of emission requirements. Expectations are that this will force most engine builders to incorporate Exhaust Gas Recirculation (EGR). Several studies of the impact of EGR on lubricant degradation have shown increased levels of contamination with soot particles and acidic components. Both of these could lead to changes in lubricant requirements. The industry is developing a new specification for diesel engine lubricants, PC-9, using test procedures incorporating engines with EGR.
Technical Paper

Diesel Engines Using Low Sulfur Fuel Showing Excellent Performance and Durability with Reduced TBN Lubricants

More stringent emission legislation has been a driver for changes in the design of Heavy Duty Diesel engines since the 1980s. Significant gains have been made over the years but, in 2007 and again in 2010, diesel engines in North America will have to meet even more stringent requirements for particulate matter and nitrogen oxide emissions. A reduction of the sulfur level in diesel fuel to a maximum of 15 mg/kg has been mandated as an enabler for new diesel engine exhaust gas after-treatment systems. Many studies have been published on the impact of the use of low sulfur diesel fuel. The focus of most of these studies has been on the possible impact on exhaust gas after-treatment system durability, but little has been documented on lubricant degradation and on the long term impact on engine durability. The objectives of the field test discussed in this paper were to evaluate the impact of low sulfur fuel and of a reduction in the TBN of the lubricant on lubricant degradation.
Technical Paper

Effects of Exhaust Gas Recirculation on the Degradation Rates of Lubricating Oil in a Heavy-Duty Diesel Engine

The specific goal of this project was to determine if there is a difference in the lube oil degradation rates in a heavy-duty diesel engine equipped with an EGR system, as compared to the same configuration of the engine, but minus the EGR system. A secondary goal was to develop FTIR analysis of used lube oil as a sensitive technique for rapid evaluation of the degradation properties of lubricants. The test engine selected for this work was a Caterpillar 3176 engine. Two engine configurations were used, a standard 1994 design and a 1994 configuration with EGR designed to meet the 2004 emissions standards. The most significant changes in the lubricant occurred during the first 50-100 hours of operation. The results clearly demonstrated that the use of EGR has a significant impact on the degradation of the engine lubricant.
Technical Paper

Enhanced Fuel Economy Retention from an Ultra-Low Ash Heavy Duty Engine Oil

Diesel particulate filters are remarkably efficient in reducing emissions of particulate matter from heavy-duty diesel engines. However, their efficiency and performance are negatively impacted by contaminants derived from consumed engine lubricant. This accumulation of incombustible ash imparts a fuel economy penalty due to increased system backpressure and demand for more frequent regeneration events. This study documents a systematic evaluation of lubricant impacts on DPF ash loading, system performance, and fuel economy. A novel, ultra-low ash heavy-duty engine oil demonstrates significant advantages in aged systems when compared to tests using conventional lubricants. The ultra-low ash oil yields a significantly lower ash loading that is also more dense therefore offering extended DPF maintenance interval and potential for 3% fuel economy retention benefit. These advantages offer potential for significant reduction in cost to operate and maintain a DPF equipped engine.
Journal Article

Extending the Boundaries of Diesel Particulate Filter Maintenance With Ultra-Low Ash - Zero-Phosphorus Oil

By 2014, all new on- and off-highway diesel engines in North America, Europe and Japan will employ diesel particulate filters (DPF) in the exhaust in order to meet particulate emission standards. If the pressure across the DPF increases due to incombustibles remaining after filter regeneration, the exhaust backpressure will increase, and this in turn reduces fuel economy and engine power, and increases emissions. Due to engine oil consumption, over 90% of the incombustibles in the DPF are derived from inorganic lubricant additives. These components are derived from calcium and magnesium detergents, zinc dithiophosphates (ZnDTP) and metal-containing oxidation inhibitors. They do not regenerate as they are non-volatile metals and salts. Consequently, the DPF has to be removed from the vehicle for cleaning. Ashless oil could eliminate the need for cleaning.
Journal Article

Minimizing Diesel Particulate Filter Incombustibles by Using Ultra Low Ash - Zero Phosphorus Oil

Due to engine oil consumption, over 90% of the incombustibles in the diesel particulate filters (DPF) are derived from organometallic lubricant additives. These components are derived from calcium and magnesium detergents, zinc dithiophosphates (ZnDTP) and metal-containing oxidation inhibitors. They do not regenerate as they are non-volatile metals and salts. Consequently, the DPF has to be removed from the vehicle for cleaning. Ashless oil could eliminate the need for cleaning. This study initially focused on development of an ashless oil, but eventually concluded that this oil could not meet the valve-train wear requirements of the API CJ-4, SN/ACEA E9 oil categories. However, a zero-phosphorus oil with no ZnDTP and an extremely low sulfated ash of 0.4% demonstrated that it could meet critical engine tests in API CJ-4/ACEA/SN. The above oil, which has been optimized at 0.3% sulfated ash, has proven field performance in Cummins ISX with DPF using ultra low sulfur diesel (ULSD).
Technical Paper

Observations from Cylinder Liner Wear Studies in Heavy Duty Diesel Engines and the Evolution towards Lower Viscosity Heavy Duty Engine Lubricants

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.
Technical Paper

Optimizing Low Viscosity Lubricants for Improved Fuel Economy in Heavy Duty Diesel Engines

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.
Technical Paper

Recent Developments in GF-6, the New North American Gasoline Engine Oil Performance Category: Part 1: The New J300 Viscosity Grade; Implications and Formulation Trade-offs

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.
Technical Paper

Taking Heavy Duty Diesel Engine Oil Performance to the Next Level, Part 1: Optimizing for Improved Fuel Economy

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.
Technical Paper

The Impact of Additive Chemistry and Lubricant Rheology on Wear in Heavy Duty Diesel Engines

Increasingly severe emission legislation for heavy duty diesel engines has forced engine builders to modify their engine designs dramatically over the last few years. Some of the design modifications, such as the retardation of injection timing, resulted in higher levels of soot contamination of the crankcase lubricant. Consequently, higher wear levels were observed in the engines as a result of soot abrasion. Despite the more severe environment, there is a demand for increased engine life, which necessitates the search for ways to reduce wear. This paper describes the results of several wear studies in diesel engines. Valve train wear in engines producing high soot levels in the crankcase oil appears to be a function of soot dispersion and anti-wear film formation. Reducing the abrasiveness of the soot agglomerates and increasing the anti-wear film formation rate both result in lower valve train wear levels.
Technical Paper

The Lubricant Contribution to Improved Fuel Economy in Heavy Duty Diesel Engines

Fuel economy of internal combustion engines played an important role for engine designers for decades. For heavy duty diesel engines, over the last 10 to 15 years however, fuel economy has in some cases been sacrificed for exhaust gas emission optimizations. Now that the industry seems to have reached the point of diminishing returns in the area of reducing diesel exhaust gas emissions, the focus is back on fuel economy. This paper addresses the impact that diesel engine lubricants can have on improving fuel economy. The evaluations discussed in this paper are based on fuel economy measurements in a standardized laboratory engine test.