This part of ISO 12156 specifies a test method using the high-frequency reciprocating rig (HFRR), for assessing the lubricating property of diesel fuels, including those fuels which may contain a lubricity-enhancing additive. It defines two methods for measurement of the wear scar; Method “A” — Digital camera, and Method “B” — Visual observation.This test method applies to fuels used in diesel engines.NOTE It is not known if this test method will predict the performance of all additive/fuel combinations, including paraffinic fuels for which no additional correlation testing has been performed. Nevertheless, no data has been presented to suggest that such fuels are not within scope.