5.1 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.

5.2 Pump Lubricity Value (PLV) test results generally rank fuel effects on diesel injection system pump component distress due to wear in the same order as Bosch, Lucas, Stanadyne, and Cummins in-house rig tests.5 In these fuel/hardware tests, boundary lubrication is believed to be a factor in the operation of the component.

5.3 The PLV is sensitive to contamination of the fluids and test materials and the temperature of the test. Lubricity evaluations are also sensitive to trace contaminants acquired during test fuel sampling and storage.

5.4 Test Methods D6078 and D6079 are two methods for evaluating diesel fuel lubricity. No absolute correlation has been developed between these two test methods, or between either of these methods and the PLV.

5.5 The PLV may be used to evaluate the relative effectiveness of a fluid for preventing wear under the prescribed test conditions.

5.6 This test method is designed to evaluate boundary lubrication properties. While viscosity effects on lubricity are not totally eliminated, they are minimized.

5.7 This test can indicate whether or not an additive will improve the lubricity of a poor lubricity fuel.