A series of fluorinated alkyl aryl ethers, composed of hydrocarbon components, fluorinated alkyl groups, and ether linkage groups, were evaluated through a variety of tests to investigate lubricating properties. The basic molecular structure with tetrafluoroethoxyphenyl groups were shown to have excellent lubricities. However, ortho-position substituents to ether linkage groups diminished extreme-pressure properties. Excellent lubricities were suggested to be due to strong coordination of ether oxygen atoms to metal surfaces, and formation of iron fluorides on the metal wear surfaces. (C) 2000 Elsevier Science S.A. All rights reserved.