ULSD – no, it doesn’t stand for “Uber-Lame-Stupid Diesel,” but it might as well. It stands for “Ultra-Low-Sulfur Diesel,” and is the dominant variant of diesel fuel offered to consumers here in North America, as well as Europe.
Much like when gasoline and tetraethyl lead went their separate ways (giving us unleaded gasoline), the expected result was reduced pollution at the cost of decreased efficiency. Similarly, reducing the amount of sulfur in diesel fuel, while detrimental to potency, has the plus side of expending less harmful emissions into the atmosphere.
Sulfur is a natural product of liquid crude oil, which is how all diesel starts. Crude oil is heated to 752 degrees Fahrenheit, whereupon it becomes gaseous. The gaseous oil goes into a fractional distillation tower where, at a certain level, it cools down and becomes liquid again. Diesel’s level is between 392-662 degrees Fahrenheit.
Sulfur that is embedded within the diesel fuel, and when burned, causes particulates (soot) and gives us the “rolling coal” look that many diesel enthusiasts enjoy on their rigs. The government, however, exercises jurisdiction through the EPA and has decided that soot can no longer be produced from the factory.
Per fueleconomy.gov, ULSD is supposed to have 97-percent less sulfur than low-sulfur diesel (LSD), which was the previous diesel fuel offered at fueling stations. In terms of hard numbers, this means that sulfur content drops to 15 ppm or less, where LSD was 500 ppm or less. ULSD was meant to coincide with the standards implemented in 2007 that made selective catalyst reduction (SCR) mandatory in all diesel vehicles from that year on.
To drive that point home, all fueling stations serving diesel had to switch to ULSD by December 1, 2010, or face the consequences; specifically, a fine of $32,500 per violation per day (yikes!). Additionally, the pumps had to display clear labeling saying they dispensed ULSD.
All seemed well and good – everyone could enjoy better air quality, and enjoying this earth could last a little longer. On the downside, ULSD had properties that made it bad for trucks.
Chiefly, it lacked the lubrication properties of LSD, partly provided by the aforementioned sulfur. Without sulfur, the fueling systems of diesel trucks would wear out faster than before. Another point was that it contained less BTUs (British Thermal Units) than LSD. This was somewhat of a moot point, as it only dropped by 1-2 percent, equating to an additional $500 over the course of 100,000 miles, but it was a loss nonetheless.
One more point was its hygroscopic nature, making it inclined to absorb water from the air. As any diesel guy will tell you, having water in the fuel system is devastating, as it can corrode fuel tanks, pumps, and injectors, as well as plug up filters.
So, this is the reality we live in – use diesel that absorbs moisture and slowly kills your truck, or breathe air that slowly gives you cancer and lung disease. The government already made its decision, but where do you stand on ULSD? Feel free to leave a comment below.