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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.

Two engine dynamometer test protocols are compared for their ability to discriminate and duplicate the field phenomenon of engine non-start due to combustion chamber deposit (CCD) flaking. The first, a protocol based on a 625 hour deposit accumulation cycle, has been shown in prior work [1, 2] to reflect field experience and discriminate the effects of various fuel additive treatments. The second, a protocol based on a 60 hour deposit accumulation cycle, was developed in an attempt to significantly reduce the time, and thus cost, of testing. Results indicate the shorter protocol is repeatable and has similar discrimination with respect to fuel and fuel additive impact on the no-start phenomenon. There are, however, differences in the results that indicate there may be a severity difference between the tests. The tests both show there are clearly differences in the engine no-start impact of deposits formed by fuel and additives. It is also found that while all CCD's produce flaking, and in all cases significant cylinder pressure loss occurs in one or more cylinders during cold start, neither of these observations correlate with start or no-start results. Clearly, engine no-start due to CCD flaking is a complex phenomenon that cannot be easily accounted for via secondary measurements.