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Forthcoming on-highway 2005/2007 European and North American emission regulations will require modern diesel engines to be equipped with Diesel Particulate Filters (DPF) capable of trapping up to 99% of the exhaust particulate matter. Since diesel particulates (soot) accumulate in the filter over time, the overall system needs to be regenerated by attaining the ignition temperature of soot, which in the presence of oxygen is >600 °C. Catalyzed DPFs regenerate at temperatures as low as ∼300 °C. One of the major issues facing OEMs, aftertreatment system manufacturers, and lubricant formulators is the potential effects of the lubricant-derived ash deposits and their impact on a pressure increase across filters, as well as overall filter performance and its service characteristics. In the present study, several lubricant-formulating additive variables, metal detergent type, antiwear additive (ZDP) type and level, the presence of boron as well as the effect of noble metal concentration in catalyzed DPF were examined. The paper explores ramifications of these formulation variables, especially the effects of lubricant chemistry, on DPF balance point temperature, ash deposits distribution and recovery. Findings identify the impact of lubricant derived species on soot combustion, ash type and presence of volatile components within the filter deposits.

A series of heavy-duty diesel, fired engine tests were run using coated valve train components in combination with low emission diesel engine crankcase oils. Examination of coated rocker arm and corresponding, uncoated crosshead surfaces, showed that greater crosshead wear was encountered using a physical vapor deposition (PVD) chromium nitride coating, as compared with that observed using a tungsten carbide PVD composition, or an uncoated rocker arm surface. Good coating adhesion was observed with both coatings, with no adverse effects on neighboring, uncoated surfaces. Tungsten carbide in combination with the first of two low-emission engine oils out performed either of the oils used in combination with chromium nitride. Test parameters are summarized along with key engine data obtained. Observations from surface characterization of representative rocker arm and mating crosshead components, using optical and scanning electron microscopy coupled with energy dispersive spectrometry also are highlighted and discussed.Copyright © 2005 by ASME