Updated - November 08, 2006

More Information on ULSD...

First, I want to concentrate on the loss of the sulfur and why this is important to you. Sulfur is an Extreme Pressure (EP) lubricant. It is regularly added to lubricating oils and greases to increase the lubricity and to raise the amount of pressure that the lubricant can handle before the lubricating molecular barrier begins to break down. Sulfur has always been a vitally important factor in providing lubrication to diesel engine fuel pumps, fuel injectors, and to a lesser degree engine valves.

The reduction now being made takes on-highway diesel from less than 500 ppm to less than 15 ppm, which for all practical purposes eliminates sulfur as a lubricant in the fuel.

There are several methods of determining lubricity in fuels. The most common are: Ball on Cylinder Lubricity Evaluator (BOCLE), Scuffing Load on Ball Lubricity Evaluator (SLBOCLE), and High Frequency Reciprocating Rig (HFRR). The HFRR has emerged as the world standard and has been adopted by the ASTM and all of the engine manufacturers as the de-facto standard for measuring lubricity of fuels. HFRR ratings are counter-intuitive with the lower number showing better lubricity than a higher number.

On an HFRR test the number given is a measurement of the scar diameter (microns) produced during the test. The larger the scar diameter, the lower the lubricity, the smaller the scar the better the lubricity

Here is a few ASTM HFRR Standards...

In the matter of Lubricity the ASTM after many years of discussion, has set its standard at HFRR 520 for diesel fuel as a minimum.

Amount of lubricant in diesel fuel at 1 Gallon and 35 Gallons of ULSD diesel fuel.

When you look at it from this stand point the amount of lubricants have been reduced to next to nothing.