Originally Posted by c00nhunterjoe

the ulsd's lubricity is not a concern. it is the same as the old diesel. the lack of mileage is from the new fuel however its not because of sulfur, its because of the way it burns, its not as "hot" as the old fuel.

Originally Posted by NATSO

OPERABILITY:

Q: How will ULSD affect fuel economy?
A: The process to remove the sulfur also reduces aromatics and density of the fuel, which lowers the energy content by about 1 percent. This should result in decreased power and fuel economy. One large fleet conducted a comparative test using ULSD and found a 2 percent fuel economy penalty.

Q: How will ULSD affect the operations of the existing fleet?
A: Engine manufacturers are not anticipating that existing engine owners will have to make any changes to their equipment to operate the new fuel. ULSD is expected to be fully compatible with the existing fleet; however, older vehicles (pre 1993) may require preventive maintenance in the form of upgrading certain engine and fuel system seals that may not perform well in the absence of sulfur. Studies on test fleets have indicated that fuel system leaks are not exclusive to a particular engine type, fuel type or geographic region. It is anticipated that that only a very small fraction of the vehicles may be affected. Check with truck dealers for additional information.

ULSD may act as a solvent when introduced into an older truck, necessitating minor maintenance in the form of a fuel filter change.

ULSD requires lubricity additives and corrosion inhibitors to prevent increased engine wear. With these additives, ULSD should help to increase engine life, and intervals between oil changes. ULSD also improves cold start ability, and reduces white smoke.

Q: Can conventional diesel be burned without operational problems in 2007 cars and trucks?
A: No. EPA regulations prohibit the use of conventional diesel fuel in highway diesel engines beginning with the 2007 model year. In 2007 models, highway diesel engines will be equipped with advanced exhaust after treatment devices for tighter control of Particulate Matter and NOx emissions. These devices could experience significant reductions in emission control efficiency and durability issues if allowed to be operated on conventional diesel fuel. Using conventional diesel in a vehicle designed for ULSD may invalidate the manufacturer’s warranty. The trucking industry does not yet have sufficient operational experience with the post-2007 truck technologies to accurately predict the impact of various misfueling scenarios.

Q: What is being added to the fuel to maintain lubricity?
A: Lubricity is a measure of the fuel’s ability to lubricate and protect the various parts of the engine’s fuel injection system from wear. The processing required to reduce sulfur to 15 ppm also removes naturally-occurring lubricity agents in diesel fuel. To manage this change, the American Society for Testing and Materials (ASTM) adopted the lubricity specification defined in ASTM D975 for all diesel fuel which went into effect on January 1, 2005. Fuel suppliers are adding lubricity agents to ULSD in the distribution system to ensure that it meets these lubricity specifications when dispensed at the retail pump.

There is no need for the consumer to add lubricity agents to the fuel tanks of their vehicles.

Q: Will truck engines be harmed if ULSD and biodiesel are mixed?
A: Biodiesel made from soy should not exceed 15 ppm of sulfur and therefore may be used as an additive to improve the lubricity of ULSD. ULSD and biodiesel fuel have different properties, particularly biodiesel thickens at higher temperatures than petroleum-based diesel. Because of this, special care needs to be taken when blending the two fuels together, particularly in cold weather. Consequently, biodiesel and ULSD should be blended by the distribution facility rather than mixed in an individual vehicle’s fuel tank. Engine manufacturers have stated that low percentage blends of biodiesel (<5%) should not adversely impact operability, provided that the fuel complies with the applicable ASTM standards.

Q: May retailers continue to blend No. 1 diesel (kerosene) to improve cold weather performance?
A. Yes, but only if the kerosene is ultra-low sulfur (<15 ppm) may it be blended with ULSD. EPA regulations prohibit the blending of fuels or use of additives that will contaminate ULSD. Refiners have announced plans to produce No. 1 diesel that is ultra low sulfur to improve the cold flow properties of ULSD. Care should be taken to ensure that kerosene used in a post-2007 truck is ULSD compliant.