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Conventional diesel fuel has been in the market for decades and used successfully to run diesel engines of all sizes in many applications. In order to reduce emissions and to foster energy source diversity, new fuels such as alternative and renewable, as well as new fuel formulations have entered the market. These include biodiesel, gas-to-liquid, and alternative formulations by states such as California. Performance variations in fuel economy, emissions, and compatibility for these fuels have been evaluated and debated. In some cases contradictory views have surfaced. “Sustainable”, “Renewable”, and “Clean” designations have been interchanged. Adding to the confusion, results from one fuel in one type of engine such as an older heavy-duty engine, is at times compared to that of another type such as a modern light-duty. This study was an attempt to compare the performance of several fuels in an identical environment, using the same engine, for direct comparison.

Conventional diesel fuel (1) has been on the market for decades and used successfully to run diesel engines of all sizes in many applications.* In order to reduce emissions and to foster energy source diversity, new fuels such as alternative and renewable, as well as new formulations, have entered the market. These include biodiesel, gas-to-liquid, and alternative formulations by states such as California. Performance variations in fuel economy, emissions, and compatibility for these fuels have been evaluated and debated. In some cases, contradictory views have surfaced. “Renewable” and “clean” designations have been interchanged. Adding to the confusion, results from one fuel in one type of engine, such as an older heavy-duty engine, is at times compared to that of another type, such as a modern light-duty engine.

Fleet customers demand reduced operating costs. This necessitates the development of engine oils which can provide maximum fuel economy and extended oil drains, while still maintaining engine durability. This is particularly important in diesel engines produced since October 1998. These engines use retarded timing to meet EPA's emission requirements and, as a consequence in some cases, generate high soot levels in the engine oil. Extended oil drains in 1995 Caterpillar 3406E and 1996 Detroit Diesel Series 60 engines found no statistical difference in fuel economy or wear between a synthetic SAE 5W-40 and an SAE 15W-40 using API Group II base stocks. Both oils had the same API CG-4/SJ quality level. Soot levels at oil drains of 40,000-50,000 miles (64,372 - 80,465 km) ranged from 0.5-1.2%.

API's Engine Oil Licensing and Certification System has implemented Provisional Licensing in response to a shortage of parts for the Sequence IIIE engine test. A Task Force delegated by the ASTM Sequence II/III Surveillance Panel was asked to develop a process, if appropriate, for the use of mathematical models as a substitute for the Sequence IIIE engine test. The Task Force tried to develop a fair and technically justifiable system for predicting engine oil performance based on models derived from existing engine test databases. The situation appeared to some to be the ideal application for initiating and proving a virtual test approach. In the end, others said the situation was too time-constrained or limited in scope. This paper describes some of the statistical, technical, and practical issues involved in specifying a process for virtual testing. Some perspectives on these issues as discussed in the Task Force effort are explored.

Conventional diesel fuel has been in the market for decades and used successfully to run diesel engines of all sizes in many applications. In order to reduce emissions and to foster energy source diversity, new fuels such as alternative and renewable, as well as new fuel formulations have entered the market. These include biodiesel, gas-to-liquid, and alternative formulations by states such as California. Performance variations in fuel economy, emissions, and compatibility for these fuels have been evaluated and debated. In some cases contradictory views have surfaced. “Sustainable”, “Renewable”, and “Clean” designations have been interchanged. Adding to the confusion, results from one fuel in one type of engine such as an older heavy-duty engine, is at times compared to that of another fuel in another type such as a modern light-duty engine. This study was an attempt to compare the performance of several fuels in identical environments, using the same engine, for direct comparison.

Researchers and cooperative groups worldwide conducted research and developed several test methods to gauge the lubricity of diesel fuel. This was necessary because the more recent fuel specifications require a higher level of hydrotreating which in turn can result in a reduction of diesel fuel lubricity. An appropriate test method was needed to enable measures to restore fuel lubricity and to enable fuel suppliers to comply with the newly adopted diesel fuel lubricity specification. The current test method that is used by most regions of the world is the High Frequency Reciprocating Rig, HFRR. Although this test method was developed and selected by the ISO group originally, and is fundamentally the same, it has been adopted in slightly different forms by regions of the world. One common element in all forms of the test method is its poor precision when compared to test methods for other fuel properties.