A complex solution

With all the attention being paid to 2007 diesel engines, you need to guard against developing tunnel vision, focusing all of your attention and questions on the engines themselves. If you don't see the entire picture, you risk making some costly mistakes when it comes time to integrate the new equipment into your fleet. Certainly changes to the engines are central to meeting the new Federal emissions

With all the attention being paid to 2007 diesel engines, you need to guard against developing tunnel vision, focusing all of your attention and questions on the engines themselves. If you don't see the entire picture, you risk making some costly mistakes when it comes time to integrate the new equipment into your fleet.

Certainly changes to the engines are central to meeting the new Federal emissions requirements for medium- and heavy-duty diesels, but in reality it's requiring a complex and finely balanced combination of elements. Aftertreatment, oil and fuel are all interconnected with engine modifications in this effort. Without all four, the 2007 diesels will not perform as required.

Take some thing as seemingly simple as oil. There is a new API classification developed just for the new engines, CJ-4. It is backward compatible, meaning current engines using today's CI-4 or CI-4 Plus will be just fine with the new oil, and will be able to maintain current recommended drain intervals. However, the new oil will cost more.

At least one large fleet decided that it won't switch to the new oil in 2007. Understandably, it doesn't want two different oils in its maintenance system, and it reasons that just a small percentage of its fleet will have the new engines, so why should it switch to the more expensive oil just for that small percentage?

But then it heard something at last month's Technology and Maintenance Council (TMC) meeting that may change its plan. The diesel particulate filter (DPF) aftertreatment systems that come along with the 2007 diesels will have to be periodically cleaned of accumulated ash. At minimum, EPA says the first cleaning must be after 150,000 miles under recommended operating conditions, that is when it's used with the proper oil and fuel (ultra low sulfur diesel). Since cleaning the filter part of the DPF is somewhat complex and requires special equipment, engine manufacturers are establishing exchange programs to speed up the process and limit vehicle downtime. At the TMC meeting, public estimates for those exchanges ranged from $300 to $500.

So what does CJ-4 oil have to do with DPF filter cleaning? A major part of the reformulation for '07 was removing much of the ash content in CI-4 and older oils. While a DPF can regenerate itself by essentially burning off soot trapped by its filter, ash cannot be burned off and simply collects. Once there's enough to impede exhaust flow, the DPF lights a warning lamp on the dash, indicating it's time for a cleaning. Ignore repeated warnings long enough and the engine is programmed to de-tune itself first and eventually to shut down.

So a seemingly simple decision to cut oil costs can turn out to have expensive consequences by requiring more frequent DPF cleanings. And then there's fuel, since fuel economy will also be adversely impacted by high levels of ash in the DPF.

The emissions reductions coming in 2007 are truly impressive, and the fact that trucking will have vehicles that meet them without crippling operations is an impressive achievement. But it's not a simple one. As a truck user, you're about to find out just how difficult it was and how carefully you'll have to manage these new trucks to be sure you're getting the productivity you need as well as the air-quality we all want.


E-mail: [email protected]
Web site: fleetowner.com

TAGS: News
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