Ultra-Low Sulfur Diesel (ULSD) is the type of diesel fuel found at any gas station and offered by every fuel supplier that supplies diesel fuel. What is it?
You will first notice that this is very clear fuel, with possibly a very light amber or green tint to it. When fresh, it has very little if any odor. It may also feel a little thinner and less oily to the touch than that of low-sulfur diesel. Ultra-Low Sulfur Diesel fuel is required to have 15ppm or less, which came down from the previous Low-Sulfur Diesel at 500ppm.
The EPA had required that as of June 1, 2006, 80% of diesel fuel refined and sold for on-highway use be delivered to the distribution network at 15 parts per million (ppm) or less of sulfur. The 80% requirement was designed to accommodate some older refineries that would otherwise be forced off-line and to offer a marketing channel for low-sulfur diesel (LSD). Since then, LSD has been phased out, leaving ULSD as the main on and off-highway diesel fuel source.
In the United States, we have traditionally used #1 diesel, kerosene, to blend with or cut #2 diesel for winter use. Because of the very low 15ppm threshold for diesel, it was necessary for refineries to create and distribute an Ultra-Low Sulfur #1 fuel to continue use for winter blending. To this day, #2 diesel and #1 kerosene are still being used in diesel engines. Since the early 2000s, it has become more necessary to treat ULSD fuel with additives in order to maintain quality, reduce water contamination, and keep this fuel liquid in the cold winter months.
The primary diesel fuel is and will continue to be #2 ULSD, and using kerosene as an aid in the winter to prevent gelling is still very common. Kerosene offers significantly less BTUs (energy) per gallon, less lubricity, less viscosity compared to #2 ULSD. You are paying significantly more and getting significantly less benefit.
In the US the EPA regulates only sulfur content. The other specifications for diesel fuels are determined by the American Society for Testing of Materials (ASTM).
One of the biggest concerns with ULSD is the severe reduction in lubricity resulting from the removal of sulfur. The current method for measuring lubricity worldwide is known as High Frequency Reciprocating Rig (HFRR). This testing device uses vibration between metal surfaces to determine the lubricating characteristics of fluids. With HFRR, a lower number is better.
- High Sulfur #2 diesel provides a HFRR of 300-350
- Low Sulfur #2 diesel provides a HFRR of 350-390
- Ultra-Low Sulfur #2 diesel provides a HFRR of 600-800
- Ultra-Low Sulfur #1 diesel provides a HFRR of 700-900
The Engine Manufacturers Association (EMA) has determined that it can accept an HFRR of 460 or lower. The European Union (EU) has determined that they will accept an HFRR of 460 or lower for their fuels. The ASTM has determined that in the interest of keeping refiner’s costs as low as possible that it knows better than the engine manufacturers and the rest of the world what engines need and has therefore set its standard at HFRR 520 in the United States.
Some additional considerations:
- ULSD forms gums, varnishes, and carbon deposits more easily and quickly than LSD.
- ULSD shows a tendency to deteriorate or oxidize more quickly than LSD.
- ULSD is the result of a process of known as severe hydro-treating. This process shows a tendency to cause the fuel to be harder to treat for cold flow improvement (compared to LSD).
- ULSD is more hygroscopic than LSD had been. This tendency to hold more dissolved water will have negative effects on cold weather operations and will increase corrosion.
The considerations listed above have encouraged those operating diesel engines to seek the help of additives to improve on the shortcomings of ULSD. We at Enertech Labs strived to create formulas that addressed the major concerns with ULSD. We have been improving our formulas for the last 20+ years according to trends in the diesel fuel environment in order to offer exactly what today’s high-tech engines are missing in ULSD. Products like Complete Fuel Treatment and Polar Flow in particular address the majority of the concerns listed above in one bottle.
ULSD has become the worldwide norm for diesel fuel. We believe that adding the right improvements to your fuel will save you money, downtime for breakdowns and parts replacements, and keep engines running for longer. Education regarding the fuel you’re using on a daily basis is necessary in order to identify issues in your engines that may be related to your fuel. The more knowledge, the easier it is to improve the functioning of the engines running this fuel. An ounce of prevention can go a long way in keeping your engines happy and healthy.