When the American EPA regulated sulfur out of Diesel fuel 10 years ago or so,
this created a problem. All diesel engines were designed to use the sulfur in
diesel fuel as a lubricant. Now it's gone. I don't know about you, but I
certainly didn't get the memo. Why should I? I'm a sailor not a diesel mechanic.
Although it really shouldn't be, this is a complicated subject. ULSD (Ultra Low Sulfur Diesel) fuel is the fuel currently mandated for use in all on road diesel engines. This fuel burns cleaner and is less polluting than its predecessor, called Low Sulfur Diesel Fuel. Low sulfur fuel contained less than 500 ppm of sulfur. ULSD contains 15 ppm or less.
Here's the complicated part. All diesel engines built before the switch to ULS diesel fuel, depended on the sulfur in the fuel to lubricate the engine. Since sulfur pollutes, and had to be removed, the oil refineries were mandated to replace the sulfur with their own additives. Independent random tests have shown that these required additives aren't always added to the fuel. To protect diesel engines, we have to add them ourselves.
For sailors, this should be of interest as we all depend on our diesels and at times they could be necessary to save us from life and death situations.
This is a study of some of the most popular diesel additives in a test which has ZERO bias as to the brand of the additive. Each additive was sent to the lab with random numbers on the container.
All marine diesel owners should be grateful for this study which was conducted and sponsored by Dieselplace.com. Click on the Link below for the results of their testing but I'll tell you right now that if you plan on keeping your boat, you should be adding a lubricant into your diesel fuel.
The webmaster of this website has 2 Yanmar diesels in his Catalac Catamaran and used this study to choose additives regularly used in his diesel engines.
Diesel Fuel Additive Lubricity Test
Download in PDF format