In order to improve the wear resistance properties of lubricants, at least one compound of the following formula is incorporated therein: ##STR1## Rf is a perfluorinated radical, a=0 to 10,b=0 or 1 (if a=o and c=1),c=1 to 4 (2 if a.noteq.0),m=0 or 1,n=0 or 1,X is an aryl radical,Y is a 2-hydroxy-1-phenylethyl group,R.sub.1 and R'.sub.1 each represent a hydrogen atom or an alkyl, cycloalkyl or aryl radical,R.sub.2 and R'.sub.2 each represent a hydrogen atom or an acyl residue, at least one of the symbols R.sub.1 and R.sub.2 being other than H or CH.sub.3 if the sum a+m+n=0.