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Oil is a non-renewable resource and we can not sustain our current rate of use indefinitely. Rising fuel prices, security of fuel supplies and most importantly need to reduce carbon dioxide emissions has put pressure to look at fuel economy more seriously in recent years. As already witnessed in the passenger car industry, motorcycle manufacturers are looking at engine oil as potential tool to improve efficiency and therefore reduce emissions. Carefully formulated low viscosity engine oils can bring increase in engine performance and fuel economy thereby reducing tailpipe emissions when compared with conventional, high viscosity engine oil. However, this approach needs a well balanced formulation technology and thorough testing program since in a typical modern four stroke motorcycle power-train with integrated clutch and gearbox, requirement for low engine friction should be carefully balanced with those for gearbox protection and clutch compatibility.

In an era of accelerated engine efficiency development, the ability to accurately model lubricant performance is becoming increasingly important. The general behaviour of engine lubricant viscosity with temperature is well understood and for most applications the widely accepted models of Walther and Vogel are deemed accurate enough in their prediction of decreasing viscosity with increasing temperature. However, as we move further into a digitized age it becomes apparent there is a need for a single expression higher accuracy equation which captures this behaviour to better facilitate its use in automotive engineering simulation software (Computer Aided Engineering -CAE). Ideally it would be beneficial for a viscosity model to include standard viscosity parameters in a single expression that could be calibrated directly using standard viscosity measurements that are already in common use.

As a result of extremely competitive market environment and severe emission legislation, motorcycle manufacturers are giving increased focus to the lubricant as a potential tool to improve engine performance reducing at same time tailpipe emissions and fuel consumption. However, due to very specific hardware constraints, application of highly efficient low viscosity oils to modern motorcycle requires careful formulation approach and thorough testing procedure. Previous work carried out by Castrol and described in SAE paper # 2011-32-0513 indicated that optimized, low viscosity motorcycle engine oils, formulated with dedicated technology to combine optimum clutch compatibility with engine and gearbox protection, can bring significant increase in engine power and acceleration in comparison with commercially available lubricants.

Measuring lubricant related fuel economy of internal combustion [IC] engines presents technical challenges, due to the relatively small differences attributable to lubricants. As engine technology progresses, large benefits become harder to find; so the importance of precise measurement increases. Responding to the challenge of meeting CO2 targets, many successful IC engine technologies have been deployed; these include downsizing/rightsizing[1], mechanical efficiency improvements, advanced charging and combustion systems, thermal management, sophisticated electronic control and calibration. These technologies have been deployed against a back-drop of increasingly stringent emission requirements. Increasing attention is focused on technologies which offer smaller but important contributions. The search for smaller improvements combined with growing engine and vehicle technology complexity increases the challenge of producing high quality data.

The highly competitive sport motorcycle market demands continuous increase in engine performance. At the same time, legislation in the main industrialized countries establishes stringent limits for gaseous emissions from two wheelers. As already witnessed in the passenger car industry, motorcycle manufacturers are giving increased focus to the lubricant as a potential tool to improve engine performance and reduce gaseous emissions. When compared to a conventional, high viscosity formulation, an optimized low viscosity, low friction engine oil can bring significant increase in power release and fuel economy, as well as a reduction in tailpipe emissions. However, the use of highly efficient lubricants in sport motorcycle applications needs careful evaluation since motorcycle engines with an integrated clutch and gearbox require the lubricant to achieve very precise viscometric and frictional limits.