Lubricity Improver is an essential additive used in modern high quality diesel fuels to reduce friction and wear in fuel pumps and injection equipment. The hydrotreating process required to achieve low sulphur levels, removes polar compounds that give diesels a ‘natural’ lubricity and this property is restored by use of the additive.

The HFRR test was developed in the late 1990s coincident with reductions in fuel sulphur contents. With the level now at a maximum of only 10ppm, the HFRR test and use of lubricity improver is of high importance. The HFRR procedure is included in the EN-590 specification with a wear scar measurement maximum of 460 microns. The test procedure creates metal contact between an oscillating ball and stationary plate that identifies fuels forming only a weak boundary film.

With several years operation, the specifications for wear scar have been proven to be successful in avoiding engine damage. Unfortunately, the method’s reproducibility and repeatability are poor compared to the main fuel specifications, and this can cause refiners some difficulty in certifying fuels for batch release to the market. This website provides Excel calculation routines to help refiners interpret and set blending targets for lubricity.