Abstract: The present invention relates to the preparation of antioxidant additives to lubricants and to their use in lubricating compositions. The additives according to the invention have the formula:ArAr'(H)N--(R--X).sub.a --R'Ywhere--Ar and Ar' are identical or different aromatic radicals, R and R', which are identical or different, denote a C.sub.2 -C.sub.18 linear or branched alkylene radical, X denotes an oxygen or sulphur atom or an --NH group, a is an integer between 0 and 5 and Y is chosen from the group consisting of --NR.sub.1 R.sub.2, where R.sub.1 and R.sub.2, which are identical or different, denote a hydrogen atom or a C.sub.1 -C.sub.12 alkyl, alkenyl, cycloalkyl or arylalkyl radical --N.dbd.CH--Ar.sub.1 where Ar.sub.1 is an aryl radical containing at least one phenolic group --NR.sub.1 --CO--Ar.sub.1 and ##STR1## where R.sub.3 denotes a saturated or unsaturated, linear or branched alkyl radical.

Abstract: This invention relates to additives to lubricants with antiwear and extreme-pressure effect consisting of asymmetric dihydrocarbyl polysulphides containing a hydrocarbyl polysulphide group R-S.sub.x - in a vicinal position of a secondary or tertiary alcohol, and to lubricating compositions containing these additives. The additives are prepared by reaction of a basic salt of a hydrocarbyl (poly)sulphide either with a compound containing at least one epoxy group or with an alpha-hydroxylated organic thiosulphate.