Stabilized lubricants based on polyethers containing diphenylamine derivatives of the formula ##STR1## in which R.sup.1 denotes hydrogen, a straight-chain or branched C.sub.4 to C.sub.12 -alkyl group, a straight-chain or branched C.sub.4 to C.sub.12 -alkylene group, a C.sub.7 to C.sub.12 -aralkyl group, a C.sub.7 to C.sub.12 -aralkylene group, a C.sub.5 to C.sub.12 -cycloalkyl group which is optionally substituted by C.sub.1 to C.sub.6 -alkyl, -alkenyl, -cycloalkyl or -cycloalkenyl, or a C.sub.5 to C.sub.12 -cycloalkenyl group which is optinally substituted by C.sub.1 to C.sub.6 -alkyl, -alkenyl or -cycloalkenyl, but does not denote a hydrocarbon group derived from a terpene, in the ortho- or para-position relative to the particular N atom, n represents an integer from 1 to 29 and Y represents a bifunctional radical --A-- and optionally additionally a bifunctional radical --B--, in each case in the ortho- or para-position relative to the N atoms, wherein --A-- denotes a straight-chain or branched C.sub.4 to C.sub.12 -alkylene radical, a C.sub.7 to C.sub.12 -aralkylene radical, or a C.sub.5 to C.sub.12 -cycloalkylene radical which is optionally substituted by C.sub.1 to C.sub.6 -alkyl or -cycloalkyl, but does not denote a hydrocarbon radical derived from a terpene, and --B-- denotes --S-- or ##STR2## wherein R.sup.2 represents hydrogen, C.sub.1 to C.sub.6 -alkyl or C.sub.5 to C.sub.6 -cycloalkyl, and wherein --B-- makes up an amount of 0 to 50 mol % of Y, and if appropriate other additives.