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Gasoline direction injection (GDI) engines have been widely used by light-duty vehicle manufacturers in recent years to meet stringent fuel economy and emissions standards. Particulate Matter (PM) mass emissions from current GDI engines are primarily composed of soot particles or black carbon with a small fraction (15% to 20%) of semi-volatile hydrocarbons generated from unburned/partially burned fuel and lubricating oil. Between 2017 and 2025, PM mass emissions regulations in the USA are expected to become progressively more stringent going down from current level of 6 mg/mile to 1 mg/mile in 2025. As PM emissions are reduced through soot reduction, lubricating oil derived semi-volatile PM is expected to become a bigger fraction of total PM mass emissions.

A novel ultrasonic viscometer for in-situ applications in engine components is presented. The viscosity measurement is performed by shearing the solid-oil contact interface by means of shear ultrasonic waves. Previous approaches to ultrasonically measure the viscosity suffer from poor accuracy owing to the acoustic miss-match between metal component and lubricant [1]. The method described overcomes this limitation by placing an intermediate matching layer between the metal and lubricant. Results are in excellent agreement with the ones obtained with the conventional viscometers when testing Newtonian fluids. This study also highlights that when complex mixtures are tested the viscosity measurement is frequency dependent. At high ultrasonic frequencies, e.g. 10 MHz, it is possible to isolate the viscosity of the base, while to obtain the viscosity of the mixture it is necessary to choose a lower operative frequency, e.g. 100 kHz, to match the fluid particle relaxation time.

Improvements in vehicle fuel efficiency continue to be a significant driver for all parties involved in the operation of automotive vehicles. The cost of vehicle ownership, energy security and the need to limit greenhouse gas emissions are all factors in driving the need to improve operating efficiency. One particular area of interest is engine lubricants which are known to have a significant effect on the overall efficiency of a vehicle. The decision to move to a more fuel efficient lubricant is enhanced since the incremental cost of introducing a fuel efficient lubricant is low in comparison to the potential fuel saving leading to a favourable economic decision for a fleet owner. This paper describes a study undertaken where upon two significantly different UK buses were taken directly from the FirstGroup fleet and used for a period of two weeks for fuel economy testing. The testing centres on two commercially available engine lubricants and was completed on a test track in the UK.

It has long been understood that the piston assembly of the internal combustion engine accounts for a significant proportion of total engine friction. Modern engines are required to have better fuel economy without sacrificing durability. The pursuit of better fuel economy drives trends like downsizing, turbocharging and direct injection fuelling systems that increase cylinder pressures and create a more arduous operating environment for the piston ring / cylinder bore tribocouple. The power-cylinder lubricant is therefore put under increased stress as modern engine technology continues to evolve. The conventional approach to investigating fundamental power-cylinder tribology employs bench-tests founded on assumptions which allow for simplification of experimental conditions.

For many years, governments have driven the improvement of fuel economy in transportation through tightening legislation. This effort has focused on passenger cars, but is increasingly concerned with heavy-duty vehicles (HDV). The combination of this regulatory focus with the ever present desire for low cost of ownership in commercial vehicles is giving increased pressure to deliver more fuel efficiency from the lubricants. In order to deliver improved fuel efficiency, suitable test methodology is needed to give repeatable discriminatory results that not only help in the advance of technology, but can also highlight the magnitude of the benefit expected in real-world applications. Typical on-road driving has significant variation in fuel consumption due to driver inconsistency, changes in rolling resistance and changeable ambient conditions.

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.

Requirements to improve vehicle fuel economy continue to increase, spurred on by agreements such as the Kyoto Protocol. Lubricants can play a role in aiding fuel economy, as evidenced by the rise in the number of engine oil specifications that require fuel economy improvements. Part of this improvement is due to achieving suitable viscometric properties in the lubricant, but additional improvements can be made using friction modifier (FM) compounds. The use of FMs in lubricants is not new, with traditional approaches being oleochemical-based derivatives such as glycerol mono-oleate and molybdenum-based compounds. However, to achieve even greater improvements, new new friction modifying compounds are needed to help deliver the full potential required from next generation lubricants. This work looks at the potential improvements available from new FM technology over and above the traditional FM compounds.

Panel cokers have been used for a number of years for the evaluation of lubricant formulations with respect to thermal oxidative stability. There are, however, a number of drawbacks to the technique, particularly related to variability of the test and correlations to real engine performance. As a consequence of this, work has been undertaken to develop a new thermal oxidative screen test which provides greater flexibility and better correlation to engine tests. The glass panel coker test has been developed from a combination of several screen tests, and consists of a heated sump, where the lubricant is aerated and has NO2 additions, and from which oil is circulated over a high temperature metal surface. The apparatus largely consists of standard laboratory glassware, and as such is easily customisable to incorporate additional features, for example simulated fuel or water dilution.