Improved fuel efficiency by lubricant design: a review

There is currently a strong focus on producing increasingly fuel-efficient vehicles, both to help meet CO2 emissions reductions targets arising from the Kyoto Agreement on climate change, and, in certain countries, to avoid large government-imposed financial penalties. This paper reviews the role that lubricants can play in reducing a vehicle's fuel consumption. The paper reviews the lubricant factors that affect fuel consumption. The paper also reviews a number of engine friction models, which help to give insight into the relative importance of the different engine components to total engine friction. The paper reviews how these models compare with results from the European and US passenger car standard fuel economy engine tests now in place. The paper also reviews the issues surrounding engine durability with the lower-viscosity fuel economy lubricants that are now being developed. The majority of the paper is concerned with fuel economy in passenger car vehicles, but there is also some discussion of the issues surrounding improved fuel economy in heavy-duty diesel trucks.