Cutting through the hype about ULSD fuel.

Komos adds that TA provides ULSD at approximately 135 to 140 sites nationwide, and those sites can be found on www.tatravelcenters.com.


Perceived lower lubricity with ULSD has many maintenance professionals wondering about fuel additives. As of January 2005, all highway diesel fuel sold in the U.S. must meet a new ASTM fuel lubricity standard (ASTM D 975). Any fuel lubricity additives necessary to meet this new specification will be added by the fuel suppliers. EPA says end-users do not need to add fuel lubricity additives.

Vic Meloche, manager, Technical Sales Support for Detroit Diesel in Detroit, MI, explains that ULSD has been formulated with the necessary additives to ensure that it does not harm fuel injection parts. Detroit Diesel does not endorse any specific aftermarket additive for use in any diesel fuel.

The company says that when switching from LSD to ULSD fuel, certain types of seals can shrink and develop small leaks in the form of seepage or drips.

EPA offers that in some instances, the introduction of ULSD fuel to older vehicles may affect fuel system components or loosen deposits in fuel tanks. Maintenance managers should closely monitor diesel-powered vehicles for potential fuel system leaks or premature fuel filter plugging during the changeover to ULSD fuel.


"The process to remove sulfur removes aromatic and density properties of the fuel," says Kelly. "The average loss in energy (BTU) content is around one percent, but is within the normal variability of diesel fuel. Every batch of diesel fuel is slightly different from the next."

Detroit Diesel concurs and explains that power and fuel economy may drop up to one to three percent with the use of ULSD on these engines.

Concerns about high underhood temperatures are false worries, according to Bob Stanton, director of Polk County Fleet Management in Bartow, FL. "Current testing is showing only slightly elevated temperatures in isolated areas," he says.

Stories of cold flow issues in northern climates have also created some concerns, but there is a "winter blend" of ULSD and kerosene.

"The sophisticated fleet knows how to have the right kind of fuel for the right environment," says Stuart. "Those not in the know may have problems without the kerosene-blended fuel for cold weather driving."


Switching from Low Sulfur Diesel to ULSD will warrant using a new, lower sulfated ash oil, CJ4.

"You have to change to a CJ4 oil—an added expense," says Stuart. "This new formulation offers one percent sulfated ash and is backwards compatible."

Stuart continues, "The problem with fleets is that we like one oil, which is currently CI4. However, you don't want to use the wrong oil—warranties could be violated."


"The biggest hurdle I see is the cleaning of the traps," says Stuart. "They're about the size of a trash compactor. If they go unattended, the exhaust will become plugged."

These "traps," or Diesel Particulate Filters (DPF), are used by engine OEMs and catch particulate matter, a.k.a. soot, to burn into ash.

"DPF cleaning intervals will vary by each vehicle's duty cycle," says Stanton. "Vocational trucks (dump trucks, refuse) will likely require cleaning more often than over-the-road units due to the sustained high load/high temperature operation common to OTR applications."

Stanton offers that service times for cleaning DPFs range from 1.5 to 3 hours and typical shop tools are not sufficient for cleaning. Companies including Donaldson Company and SPX Corporation have devised DPF Cleaning Systems. The machines will be standard service items at OEM dealerships offering both on-site DPF cleaning and DPF exchanges to their customers.

"One thing maintenance folks should remember about the new vehicles is that they absolutely cannot touch the exhaust system as they used to," says Stuart. "It's a sophisticated part of the emissions and you can't modify it or get creative with it. Use OEM parts only."

He adds, "The rest will be OJT as needed. We have a much higher level of sophistication with many systems, but, a piston is still a piston and a ring's a ring. Know the basic maintenance principles and all will be well."

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