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A laboratory study was performed to assess the effectiveness of LNT+SCR systems for NOx control in lean exhaust. The effects of the catalyst system length and the spatial configuration of the LNT & SCR catalysts were evaluated for their effects on the NOx conversion, NH₃ yield, N₂O yield, and HC conversion. It was found that multi-zone catalyst architectures with four or eight alternating LNT and SCR catalyst zones had equivalent gross NOx conversion, lower NH₃ and N₂O yield, and significantly higher net conversion of NOx to N₂ than an all-LNT design or a standard LNT+SCR configuration, where all of the SCR volume is placed downstream of the LNT. The lower NH₃ emissions of the two multi-zone designs relative to the standard LNT+SCR design were attributed to the improved balance of NOx and NH₃ in the SCR zones.

High concentrations of diesel fuel can accumulate in the engine oil, especially in vehicles equipped with diesel particle filters. Fuel dilution can decrease the viscosity of engine oil, reducing its film thickness. Higher concentrations of fuel are believed to accumulate in oil with biodiesel than with diesel fuel because biodiesel has a higher boiling temperature range, allowing it to persist in the sump. Numerous countries are taking actions to promote the use of biodiesel. The growing interest for biodiesel has been driven by a desire for energy independence (domestically produced), the increasing cost of petroleum-derived fuels, and an interest in reducing greenhouse gas emissions. Biodiesel can affect engine lubrication (through fuel dilution), as its physical and chemical properties are significantly different from those of petrodiesel. Many risks associated with excessive biodiesel dilution have been identified, yet its actual impact has not been well quantified.