It used to be that diesel fuel users didn't have to worry about diesel fuel lubricity and how their diesel fuel would interact with injectors and fuel pumps. This was back in the day before the Clean Air Act of 1992, which led to the removal of 97% of the sulfur from diesel fuel. They might have worried about black smoke and fuel mileage, but not lubricity. But removing most of the sulfur created diesel fuel that didn't give the needed lubrication to these essential parts.
Then they componded the problem in 2006 by moving to ultra-low sulfur diesel fuel and removing 90% of the remaining sulfur. For those keeping score, that's a drop from 5000 parts per million of sulfur in diesel fuel to just 15 parts per million, from 1992 to the present day.
The Good News
There are a few things to feel good about in this situation. Getting the sulfur out of the fuel before its burned means no sulfur going into the atmosphere afterwards. And that means no more acid rain from diesel fuel. This is definately a good thing for everyone.
Also in the good news department is the movement towards including small amounts of biodiesel in much of the nation's diesel fuel supply. If you put less than 5% biodiesel in the diesel fuel, you don't have to label it as containing biodiesel. But that's not where the good news comes in. Biodiesel is really high in lubricity, and adding just 2-3% of ultra-low-sulfur diesel actually raises the diesel's lubricity to a level more than enough to head off any problems.
The Bad News
If you're not getting diesel fuel with bio added, you run the risk of developing injector and fuel pump wear issues. Refineries have tried to head off these problems by using lubricity additives added before the fuel reaches the gas station. But the OEM industry is finding that these lubricity standards might not be enough to head off as many potential problems as they would like. Diesel users in business should monitor their maintenance patterns and be prepared to implement preventative measures (such as incorporating lubricity improver additives) if they notice the cycles to be getting out of line with what's normal in their business.
This post was published on June 26, 2014 and was updated on May 1, 2019.