Lubricity is defined as the ability of a liquid to provide hydrodynamic and/ or boundary lubrication to prevent wear between moving parts; or the ability to reduce friction between solid surfaces in relative motion. Thus, diesel fuel with poor lubricity will contribute to wear and tear in the fuel system of diesel engines. Various international standard specifications for diesel fuel, such as the European Standard Specification for Diesel Fuel (EN590), Worldwide Fuel Charter and US Diesel Fuel Specification (ASTM D975) specify the wear scar diameter (WSD) from a high frequency reciprocating rig (HFRR) of 400 to 520 µm as the acceptable limits (Table 1). The referee method for measuring lubricity is the High Frequency Reciprocating Rig (HFRR) test (ASTM D 6079), which measures the wear scar diameter on a specimen ball rubbed against a disk under specified conditions. As bigger scar indicates poorer lubricity, the standards specify the maximum diameter.

Main Research: Yung Chee Liang