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Technical Paper

Acid Neutralization and Engine Hardware Corrosion Protection through Heavy-Duty Diesel Lubricant Additive Chemistry

One of the primary functions of modern heavy duty diesel (HDD) lubricants is to protect the engine against corrosion, which is typically accomplished by additives providing alkaline material, commonly represented as total base number (TBN). The majority of the TBN in HDD lubricants comes from ash-containing over-based detergents, with various metallic base and soap chemistries. In this publication, we discuss several overbased detergents and their efficacy in acid neutralization, as well as the resulting impact on corrosion protection. The performance differences are compared in a number of stationary API CJ-4 and CK-4 HDD engine screener tests. Furthermore, these results are confirmed with field trial data, including a comparison of CJ-4 oils with the upcoming API FA-4/CK-4 oils. The selection of overbased detergent type provides varying levels of acid neutralization and corrosion protection.
Technical Paper

Assessment of Ageing Mechanisms in Lubricants and Their Effects on Retained Low Temperature Pumpability of Top Tier Oils

Low temperature pumpability is an important requirement for engine lubricants. It ensures that sufficient oil reaches the parts of the engine requiring wear protection on engine start-up. Until recently, most industry emphasis has been on the low temperature pumpability of the fresh oil. However, the oil can undergo a number of changes during its lifetime in the engine which adversely affect low temperature pumpability. Industry stakeholders are now expressing concerns about the potential risk of engine failures due to deterioration of low temperature pumpability of oils during their life cycle in the engine. Concerns have also been raised over the last few years that the move to Group III base stocks, while improving many of the properties of oil formulations, may also impact their retained low temperature pumpability.
Journal Article

Controlling Low-Speed Pre-Ignition in Modern Automotive Equipment Part 3: Identification of Key Additive Component Types and Other Lubricant Composition Effects on Low-Speed Pre-Ignition

Market demand and evolving global legislation are forcing OEMs to improve fuel consumption and reduce CO2 emissions. Downsizing in direct injection gasoline engines has been a common strategy towards achieving this goal, but this requires increased boost pressures to maintain power. The increased boost pressures are creating a new abnormal combustion phenomenon known as Low-Speed Pre-Ignition (LSPI). Lubricants and fuels have been implicated as significant influencers of LSPI frequency and intensity. Part 1 of the series described the development of a statistical approach for measuring and quantifying LSPI activity. This statistical approach was shown to be consistent and repeatable. Part 2 of the series further refined the methodology from Part 1 to reduce the frequency of false positives and negatives. A baseline lubricant was used in both of these papers to demonstrate the robustness of this methodology.
Technical Paper

Controlling Low-Speed Pre-Ignition in Modern Automotive Equipment: Defining Approaches to and Methods for Analyzing Data in New Studies of Lubricant and Fuel-Related Effects (Part 2)

In recent years, an abnormal combustion phenomenon called low-speed pre-ignition (LSPI) has arisen from the downsizing of gasoline engines in order to improve fuel economy and comply with global CO2 legislation. The type and quality of the fuel and lubricant has been found to influence LSPI occurrence rates. A methodology for studying LSPI has been implemented, and a rigorous statistical approach for studying the data from a stationary engine test can provide consistent results as shown in Part 1 of the series. LSPI events can be determined by an iterative statistical procedure based on calculating the mean and standard deviation of peak pressure (PP) and crank angle location of 2% mass fraction burned (MFB02) data, determining cycles with parameters which exceeded n standard deviations from the mean and identifying outliers. Outliers for the PP and MFB02 metrics are identified as possible LSPI events.
Technical Paper

Development of New CNG-Gasoline (Bi-fuel) Lubricant, by Taxi Fleet Screening Test and Field Trial in Thailand

An internal combustion engine operating on compressed natural gas (CNG) as fuel is usually under higher thermal stress compared to the same engine using gasoline fuel. This leads to various concerns on the operation of CNG engine and the performance of the lubricant, such increased wear, accelerated total base number depletion, and faster deterioration of the lubricant. Engine oil intended for compressed natural gas (CNG)-gasoline bi-fuel passenger car application must therefore be formulated to withstand the varied and often severe operating conditions, as well as maintain superior lubrication control and prolong engine life. PTT Public Company Limited (PTT) has developed a new CNG-gasoline lubricant meeting API SN/GF-5 performance category that is able to address the various operating concerns of bi-fuel passenger car engines, and at the same time provides extended oil drain interval (ODI) capability.
Technical Paper

Evaluation of SAE 0W-20 GF-4 Prototype Formulation in Severe Taxi Fleet Service

This paper reviews the relative performance of prototype SAE 0W-20 and SAE 5W-20 ILSAC GF-4 [1, 2] mineral oils in severe taxi fleet service. Both oils contained the same additive technology, formulated to 0.05% mass Phosphorus. This level was targeted to gain field experience with oils formulated to meet proposed chemical limits for the ILSAC GF-4 specification [1, 2]. Though the limits in the final ILSAC GF-4 specification were increased to 0.08% mass Phosphorus, the 0.05% mass Phosphorus maximum is again proposed for the ILSAC GF-5 specification [3]. Used oil Chemical and Physical analysis was carried out at both interim and final drains (10,000 miles). Oil and fuel consumption were also monitored during the test. After a total mileage accumulation of 100,000 miles per vehicle, engine teardowns and physical ratings were performed on key engine components. It was concluded the performance of both lubricants was equivalent and acceptable.
Journal Article

Extending SAE J300 to Viscosity Grades below SAE 20

The SAE Engine Oil Viscosity Classification (EOVC) Task Force has been gathering data in consideration of extending SAE J300 to include engine oils with high temperature, high shear rate (HTHS) viscosity below the current minimum of 2.6 mPa⋅s for the SAE 20 grade. The driving force for doing so is fuel economy, although it is widely recognized that hardware durability can suffer if HTHS viscosity is too low. Several Japanese OEMs have expressed interest in revising SAE J300 to allow official designation of an engine oil viscosity category with HTHS viscosity below 2.6 mPa⋅s to enable the development of ultra-low-friction engines in the future. This paper summarizes the work of the SAE EOVC Low Viscosity Grade Working Group comprising members from OEMs, oil companies, additive companies and instrument manufacturers to explore adoption of one or more new viscosity grades.
Journal Article

Field and Bench Study of Shear Stability of Heavy Duty Diesel Lubricants

Global environmental and economic concerns of today's world dictate strict requirements for modern heavy duty engines, especially in emissions, noise control, power generation, and extended oil drain intervals. These requirements lead to increased stresses imposed on lubricants in modern heavy duty engines. At the same time, the original equipment manufacturers (OEMs) desire additional fuel economy from the lubricating oil, requiring the use of lower viscosity lubricants to minimize frictional losses in the engine. These lower viscosity oils are subjected to increased stresses in the engine and need to provide robust performance throughout their lifetime in order to protect engine parts from wear and damage. One of the most important lubricant qualities is to maintain viscosity throughout the drain interval and thus provide continuous engine protection.
Technical Paper

In-Service Low Temperature Pumpability: Field Performance vs. Bench Tests

The most important property of the engine oil is its ability to reach all engine parts. Once there, it can build an oil film which protects these parts from wear and ultimately from destruction. No other lubricant property is relevant if the oil cannot be delivered to the critical engine parts. Thus engine oil pumpability, especially pumpability at low temperatures when the viscosity of the lubricant is the highest, is crucially important. The crankcase lubricant industry has recognized this, in requiring good low temperature pumpability for the last three decades. While good low temperature properties of the fresh oils are a necessary requirement for a lubricant, they are not sufficient to ensure the lifetime performance of the oil in the engine. The oil gradually ages in the engine and its properties, including low temperature pumpability, change.
Technical Paper

Measuring Fuel Efficiency in Various Driving Cycles: How to Get Maximum Fuel Economy Improvement from the Lubricant

Increasing vehicle efficiency has been one of the key drivers of the automotive industry worldwide due to new government emission legislations and rising fuel costs. While original equipment manufacturers (OEMs) are responding with innovative hardware designs for new models, lubricant companies are developing additive solutions to reduce frictional losses in the engine thereby increasing fuel economy of both new and existing vehicles. Fuel efficiency of the vehicle can be measured in a variety of driving cycles, including the New European Driving Cycle (NEDC), Japanese JC-08, and FTP-75 (Federal Test Procedure). The type of vehicle used in fuel economy evaluation in the same cycle plays a significant role. Fuel consumption rates for the same vehicle measured in these driving cycles vary due to the differences in the cycles. Thus, to assess the effect of the lubricant on fuel efficiency in various cycles, the fuel consumption is measured relative to a reference oil.
Technical Paper

Next Generation Diblock Viscosity Modifier for Heavy Duty Diesel Engine Lubricants

An unprecedented global focus on the environment and greenhouse gases has driven recent government regulations on automotive emissions across the globe. To achieve this improvement, Original Equipment Manufacturers (OEMs) have advocated a progressive move towards the use of low viscosity grade oils. However, the use of lower viscosity grades should not compromise engine durability or wear protection. Viscosity modifiers (VM) - polymeric additive components used to tailor the lubricant’s viscometric properties - have been viewed as a key enabler for achieving the desirable balance between fuel economy and engine durability performance. Self-assembling diblock copolymers represent a unique class of VMs, which deliver superior shear stability due to their tunable association/dissociation in the lubricating oil. Superior shear stability ensures that the oil viscosity and its ability to offer reliable engine protection from wear is retained over the life of the oil in the engine.
Journal Article

The Effect of Low Viscosity Oil on the Wear, Friction and Fuel Consumption of a Heavy Duty Truck Engine

This paper describes the results of a series of tests on a heavy-duty truck diesel engine using conventional and low viscosity lubricants. The objectives were to explore the impact of reducing lubricant viscosity on wear, friction and fuel consumption. The radiotracing Thin Layer Activation method was used to make on-line measurements of wear at the cylinder liner, top piston ring, connecting rod small end bush and intake cam lobe. The engine was operated under a wide range of conditions (load, speed and temperature) and with lubricants of several different viscosity grades. Results indicate the relationship between lubricant viscosity and wear at four critical locations. Wear at other locations was assessed by analysis of wear metals and post test inspection. The fuel consumption was then measured on the same engine with the same lubricants. Results indicate the relationship between oil viscosity and fuel consumption under a wide range of operating conditions.
Technical Paper

The Impact of Evolving Automatic Transmission Fluid Specifications on Base Oil Selection

Automatic transmission fluid (ATF) performance is determined by the choice of lubricant basestocks and additives used to formulate the fluid. The lubricant basestocks employed set the fundamental low temperature capabilities and resistance to oxidation of the fluid. Over the last decade, ATF specifications issued by the major North American transmission builders have required significant improvements in low temperature fluidity and oxidation stability. These required improvements have begun to limit the number of basestocks capable of producing suitable fluids. The practical impact of this evolution is that API Group I basestocks are rapidly becoming incapable of producing the new generation of ATFs. Recently issued, and proposed, specifications will clearly continue this trend. Future ATF formulations may well be forced to move to API Group II, Group III and/or synthetic base fluids to meet these increasing performance requirements.
Technical Paper

Understanding Lubricant Requirements of Hybrid-Electric Vehicles

Innovation of Hybrid-Electrical Vehicles (HEV) has led to consumer demand for their fuel efficiency and emissions benefits among a growing segment of the population. An HEV is driven by a combination of an internal combustion engine and an electric motor. A distinguishing feature of the HEV is the ability to turn off the IC engine when the power available from the electrical system exceeds that required to propel the vehicle. This results in net cooler operating temperatures of the IC engine and more frequent starts of the engine. This research program was initiated to determine if the HEVs have any special lubrication requirements relative to those used in non-hybrid variety, and to look for opportunities to develop lubricant systems specifically tailored for such vehicles.