Real World Study of Diesel Particulate Filter Ash Accumulation in Heavy-Duty Diesel Trucks

In April 2003, a small field study was initiated to evaluate the effect of lube oil formulations on ash accumulation in heavy-duty diesel DPFs. Nine (9) Fuel Delivery Trucks were retrofitted with passive diesel particulate filters and fueled with ultra low sulfur diesel which contains less than 15 ppm sulfur. Each vehicle operated in the field for 18 months or approximately 160,000 miles (241,401 km) using one of three lube oil formulations. Ash accumulation was determined for each vehicle and compared between the three differing lube oil formulations. Ash analyses, used lube oil analysis and filter substrate evaluations were performed to provide a complete picture of DPF operations.

The evaluation also examined some of the key parameters that allows for the successful implementation of the passive DPF in this heavy-duty application. This included examining the engine exhaust gas temperatures, the backpressures created by the DPF in this application and the lube oil consumption rate for each vehicle. The results will show that lube oil formulation or sulfated ash level has a very small impact on the performance of the passive DPF technology in this application. For well maintained vehicles with reasonable oil consumption rates, vehicle age or mileage appears to provide the best correlation for the ash accumulation rate in the filter substrate.