NEWSROOM

As a result of the 2007 federal diesel emissions standards created to reduce nitrogen oxide and soot emissions, all on-road diesel engines produced since Jan. 1, 2007 are required to be equipped with diesel particulate filters (DPF) and exhaust gas recirculation (EGR) valves.

For most fleet managers, the DPF issues are of greatest concern. Basically, a DPF traps and removes particulate matter (soot) from diesel exhaust. When exhaust gasses pass through the DPF, as much as 90 percent of the solid particulate matter is trapped. Although DPFs are designed for long life, they do require some driver involvement. It is also essential that filters be properly maintained.

The critical part of maintaining a DPF is the cleaning process. Referred to as regeneration, the process involves cleaning the filter by burning off the collected soot at a prescribed time, leaving behind a harmless ash residue. Most 2007 compliant engines feature passive and active types of regeneration, both of which require little driver interaction.

A third type, known as manual or parked regeneration, is found on medium-duty trucks that are equipped with instrument cluster indicators, which alert the driver when regeneration is needed. Although seldom required, this type of regeneration process can take approximately 20 to 40 minutes.

According to an article in Work Truck magazine (February 2008), fuel, oil and oil change intervals also can impact DPFs. Failure to comply with the following recommendations can be costly in terms of causing break downs, expensive repairs and in some cases, void warranties:
 
• Fuel. Too much soot leads to premature clogging and frequent regeneration cycles for the filter. One way to counteract the issue is to remove any controllable sources of soot or particulate matter, such as the amount of sulfur in fuel. This is where Ultra Low Sulfur Diesel (ULSD) comes into play. ULSD’s sulfur content is only 15 parts per million, down from 500 parts per million in the previous low sulfur fuel. The use of ULSD fuel is mandatory in the new generation diesel engine.

• Engine Oil. To meet 2007 emissions requirements, engine oil manufacturers have developed a new standard – CJ4, which is recommended for use in the 2007 and newer engines because it contains lower levels of phosphorus, ash and sulfur. These additives can cause more frequent service of the DPF.

• Oil Change Intervals. Adhering strictly to manufacturer recommended oil change intervals will have a huge impact on DPF longevity.

Manual cleaning also is necessary for soot that builds up over time on the channel walls of the DPF. For most light- and medium duty applications, engine manufacturers estimate the need for this manual cleaning cycle ranges from 100,000 to 150,000 miles. But, deciding whether to use special cleaning equipment to remove accumulated ash or completely replacing the filter can vary significantly depending on the specific manufacturer or truck class. Either way, the costs for both cleaning or replacement are estimated to range from several hundred dollars to more than $2,500.

Although this new technology is still in the early stages of use, there are indications that vehicles with 2007 and newer engines run as well, if not better than previous engines in terms of performance, fuel consumption, reliability and maintenance.

Aaron Lindstrom, Senior Account Executive for Enterprise Fleet Management in Washington, can be reached at (206) 423-3958.