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Future regulations have put increased focus on reducing criteria pollutant emissions, improving engine efficiency, and ensuring these benefits are maintained for the useful life of the equipment. Engine builders continue to require improved lubricants as enablers to meet these regulatory requirements. Most recently, these improvements have focused on lower engine lubricant viscosity, improved oxidative stability, and constraints on lubricant additives that interfere with emission control system performance. This study quantifies the synergistic benefits derived from combining a renewable base oil with ultra-low ash additive technology to improve fuel economy retention (FER). These benefits derive from their inherently low volatility and high oxidative stability, which limits lubricant thickening and deposits that would otherwise degrade fuel efficiency over the life of the lubricant.

Diesel particulate filters are remarkably efficient in reducing emissions of particulate matter from heavy-duty diesel engines. However, their efficiency and performance are negatively impacted by contaminants derived from consumed engine lubricant. This accumulation of incombustible ash imparts a fuel economy penalty due to increased system backpressure and demand for more frequent regeneration events. This study documents a systematic evaluation of lubricant impacts on DPF ash loading, system performance, and fuel economy. A novel, ultra-low ash heavy-duty engine oil demonstrates significant advantages in aged systems when compared to tests using conventional lubricants. The ultra-low ash oil yields a significantly lower ash loading that is also more dense therefore offering extended DPF maintenance interval and potential for 3% fuel economy retention benefit. These advantages offer potential for significant reduction in cost to operate and maintain a DPF equipped engine.

Over the last two decades, global emission regulations have become more stringent and have required the use of more advanced fuel injection systems. This includes the use of tighter tolerances, more rapid injections and internal components actuated by weaker injection forces. Unfortunately, these design features make the entire system more susceptible to fuel contaminants. Over the last six years, the composition of these contaminants has evolved from hard insoluble debris, such as dust and rocks, to soluble chemical contaminants. Recent research by the diesel engine manufacturers, fuel injection equipment suppliers and the fuel and fuel additive industry has discovered a major source of the soluble chemical contaminant that leads to injector deposits to be derived from cost effective and commonly used additives used to protect against pipeline corrosion.

A technique for rapid in situ measurement of the fuel dilution of oil in a diesel engine is presented. Fuel dilution can occur when advanced in-cylinder fuel injection techniques are employed for the purpose of producing rich exhaust for lean NOx trap catalyst regeneration. Laser-induced fluorescence (LIF) spectroscopy is used to monitor the oil in a Mercedes 1.7-liter engine operated on a dynamometer platform. A fluorescent dye suitable for use in diesel fuel and oil systems is added to the engine fuel. The LIF spectra are monitored to detect the growth of the dye signal relative to the background oil fluorescence; fuel mass concentration is quantified based on a known sample set. The technique was implemented with fiber optic probes which can be inserted at various points in the engine oil system. A low cost 532-nm laser diode was used for excitation.