Significance and Use Diesel fuel injection equipment has some
reliance on lubricating properties of the diesel fuel. Shortened
life of engine components, such as diesel fuel injection pumps
and injectors, has sometimes been ascribed to lack of lubricity
in a diesel fuel. The trend of HFRR test results to diesel
injection system pump component distress due to wear has been
demonstrated in pump rig tests for some fuel/hardware
combinations where boundary lubrication is believed to be a
factor in the operation of the component. The wear scar
generated in the HFRR test is sensitive to contamination of the
fluids and test materials, the temperature of the test fuel, and
the ambient relative humidity. Lubricity evaluations are also
sensitive to trace contaminants acquired during test fuel
sampling and storage. The HFRR and Scuffing Load Ball on
Cylinder Lubricity Evaluator (SLBOCLE, Test Method D6078) are
two methods for evaluating diesel fuel lubricity. No absolute
correlation has been developed between the two te