Asymmetric disulfides in lubricant compositions

A composition comprising:

• (a) at least one substrate selected from the group consisting of a lubricant and a hydraulic fluid and
• (b) an amount effective to provide high pressure and antiwear action and to reduce corrosion of at least one compound of the formula ##STR21## in which R.sup.1 and R.sup.2 are identical or different and are each an alkyl group having 1 to 30 C atoms, an unsubstituted or C.sub.1 -C.sub.8 -alkyl-substituted cycloalkyl group having 5 to 12 C atoms, or an unsubstituted or C.sub.1 -C.sub.12 -alkyl-substituted C.sub.6 -C.sub.10 -aryl group, or R.sup.1 and R.sup.2 together are an unsubstituted or C.sub.1 -C.sub.12 -alkyl-substituted alkylene group having 2 to 20 C atoms or an arylene group having 6 to 20 C atoms, and R.sup.5 and R.sup.6 are identical or different and are each an alkyl group having 1 to 30 C atoms, or R.sup.5 and R.sup.6 together are an unsubstituted or C.sub.1 -C.sub.12 -alkyl-substituted alkylene group having 2 to 20 C atoms or an alkylene group which has 2 to 10 C atoms and is interrupted by --O--, --S-- or -- NR.sup.9 --, in which R.sup.9 is H or C.sub.1 -C.sub.4 -alkyl, and X is O or S.