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Government regulations and market demands continue to emphasize conservation of fossil fuels in the transportation industry. As a consequence, any incremental improvement in fuel economy (FE) is of great importance in the automotive sector. For instance, lower viscosity lubricants have been shown to improve FE but the longevity of such improvement is compromised by viscosity increases often observed as a lubricant ages during an oil drain interval (ODI). To address this issue, an option to manage lubricant viscometrics via fuel is proposed. In order to investigate such mitigation of viscosity increase during an ODI, and potentially the delivery of an ODI-averaged FE benefit, a fleet test was conducted with a fuel-borne additive intended to control increases in lubricant viscosity. The fleet test compared a market-representative reference fuel to a fuel containing a viscosity control additive (VCA).

Planar Laser-Induced Fluorescence has been widely accepted and applied to measurements of fuel concentration distributions in IC engines. The need for such measurements has increased with the introduction of Direct Injection (DI) gasoline engines, where it is critical to understand the influence of mixture inhomogeneity on ignition and subsequent combustion, and in particular the implications for cyclic variability. The apparent simplicity of PLIF has led to misunderstanding of the technique when applied to quantitative measurements of fuel distributions. This paper presents a series of engineering methods for optimizing, calibrating and referencing, which together demonstrate a quantitative measure of fuel concentration with an absolute accuracy of 10%. PLIF is widely used with single component fuels as carriers for the fluorescent tracers.