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New Diesel Fuel Regulations

The EPA mandated (June 2006) that U.S. refineries produce Ultra-Low Sulfur Diesel (ULSD)  with the following specifications: 

  • Maximum 15 PPM Sulfur Content
  • Minimum 47 to 48 Cetane
  • Maximum 10% Aromatics

These new specifications can result In additional new fuel problems:

  • Severe Wear in the Fuel Injection System
  • Reduced Power & Fuel Economy
  • Increased Diesel Fuel Prices
  • Leaking Seals in Fuel System  

The EPA required refiners to Produce Ultra-Low Sulfur Nationwide on June 1, 2006

EPA regulations on air pollution have been the driving force behind most of the changes in diesel fuel and diesel engines since 1993.

In 1993 the sulfur content of diesel fuel was reduced from an average of 3,000 parts per million (ppm) to 500 ppm.  The aromatic content was also reduced to 35%.

These changes in diesel fuel resulted in many serious maintenance problems for diesel injection systems.  Sulfur in diesel fuel is the natural lubricant for diesel fuel injection systems.  This reduction in sulfur content caused wear in injection systems to increase 5 times the previous levels.  The reduction in aromatics caused seals in fuel pumps and injectors to shrink and leak.

These problems were in addition to the normal diesel problems, such as low cetane, water, contaminants, and biological growth.

The EPA has announced new standards for diesel fuel that promises to have similar dramatic effects.

As of June, 2006 refiners will be required to produce ultra-low sulfur diesel (ULSD) with a sulfur content of no more than 15 ppm. 

The specifications for ULSD require:

  • Sulfur content less than or equal to 15ppm
  • Minimum 48 Cetane for large refiners, 47 Cetane for small refiners
  • No more than 10% Aromatics

These are the same specifications that have been required by the California Air Resources Board (CARB) for several years and by the Texas Natural Resource Conservation Commission since October 1, 2005. 

The Effects of ULSD on Heavy Duty Diesel Engines

1. Ultra Low Sulfur (less than 15ppm) - In 1993 low sulfur diesel  (500 ppm sulfur) was 6 times drier or less lubricating than standard diesel fuel (3000 ppm sulfur).  This reduction in sulfur (the natural lubricant in diesel fuel for injector pumps and injectors) caused dramatic wear and failure.  The new ULSD is 33 times drier than today's low sulfur diesel.  Because ULSD is so dry, wear in injection systems is going to be a major problem.  Premature wear in injection systems results in failure and replacement. It also results in reduced fuel economy because worn injectors produce poor fuel spray patterns and can allow too much fuel into the combustion chamber.

2. The effects of Low Aromatic Content (10% or less) are yet to be understood.  Most engine manufacturers have replaced old seals with shrink resistant seals in injector pumps and injectors.  However, other elastomers in the fuel system may be affected.  Your fuel program does not cause these problems, nor will it solve them.

3. The increase in Cetane to 48 is a welcome improvement and will help reduce emissions, improve starting time and aid in more complete combustion.  However, this increase in Cetane still does not meet the requirements of the Engine Manufacturers Association for minimum 50 Cetane.  Cetane is rated on a scale of 30 to 60, and Cetane 50 or higher is highly preferred over a Cetane of 48.

4. Reduction of Fuel Economy.  A comprehensive study by Volvo Truck Corporation reported in Fleet Owner Magazine that the reduced energy density of ULSD results in a 2% reduction in fuel economy compared to regular low sulfur diesel.  That's because the refinery process used to take out the sulfur reduces the actual weight of the diesel fuel by 1.5%, resulting in less energy per gallon of fuel.  This news comes at a time of record fuel prices and will cost our customers at least 4¢ to 6¢ per gallon in reduced fuel economy. 

Click here to view the "Fleet Owner" Magazine Article.

These problems are in addition to the normal problems of water, biological growth, rust & corrosion, contamination, gelling, icing and poor storage stability.

CLICK HERE to view information on Fuel Expert's New Warnings on ULSD


CLICK HERE to view the offical EPA Announcement


CLICK HERE to read USA Today Article – "Formula change Worries Keep Diesel Prices Up"

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