Times Are Changing For Diesel Engines
June 1, 2007 Diesel engines are the power unit for growers, and now they are being changed to meet new exhaust emission requirements established by EPA. The emission standards are being phased in over a number of years and require changes in engine design, diesel fuel, and lubrication oils for diesel engines.
To make these emission control systems work properly, it has been necessary to reduce the sulfur level in diesel fuel. Prior to 1993, diesel fuel contained 5,000 ppm of sulfur. In that year the level was dropped to 500 ppm. On June 1, 2006, so-called ultra low sulfur (ULS) diesel fuel with only 15 ppm of sulfur was introduced. ULS diesel is the required fuel for Tier III emission engines in trucks built after January 2007. ULS diesel is necessary to reduce exhaust emissions and for the diesel particulate filter that will capture the tiny soot and ash particles in diesel engine exhaust. Use of higher sulfur level diesel fuel in 2007 truck engines will cause permanent damage to the exhaust emission system.
Although the Tier III standard is primarily for large over-the-road trucks, it is also applicable to light trucks such as pickups built after Jan. 1, 2007. Therefore, light trucks will also require ULS diesel fuel.
Get The Facts
There are several interesting facts about ULS diesel. First, as might be expected, it is more costly to produce as extra steps are necessary in the refining process to remove more sulfur. It may have slightly lower energy content than the previous diesel, which may result in higher fuel consumption. Because of this and questions about the new emission systems, many large trucking companies bought as many 2006 trucks as they could and plan to buy few 2007 trucks.
In some areas, higher sulfur diesel fuel will still be available along with ULS diesel. In California, the California Air Resources Board ruled that only ULS diesel would be available in the state.
There are other issues with ULS diesel, although they generally are of minor significance. ULS diesel may result in rubber seal leakage in older equipment because of its composition. It tends to pick up sediment from the bottom of storage tanks and an in-line filter should be added to fuel pumps.
The other major issue with ULS diesel and Tier III engines is lubricating oil. Most of the new specification engines use exhaust gas recirculation; Caterpillar uses their propriety ACERT technology along with the diesel particulate filter to meet 2007 emission standards. These changes require an improved diesel engine lubricating oil and The American Petroleum Institute (API) created a new diesel engine oil category API CJ-4 to meet the requirements of Tier III engines. Among other improvements the CJ-4 oils have less ash and offer better emission system protection that the previous API CJ-4 Plus category.
The question is, what are the benefits of the reduced exhaust emissions from diesel engines? EPA estimates the benefits will be over $70 billion annually due to reduced human health problems caused by reduced emissions. The additional costs are more expensive engines and fuel and lubricating oil cost increases.
In 2010 these standards will be applied to off-road diesel engines such as agricultural tractors and construction equiptment. At that time catalytic converters will be required for on-the-road diesel engines.
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