Metal deactivator and composition containing same

A composition comprising an oil selected from the group consisting of mineral oils and synthetic oils, said mineral oils and synthetic oils having a kinematic viscosity ranging from 10 to 10,000 cSt (40.degree. C.) and a viscosity index ranging from 80 to 250, and 0.001% to 10.0% by weight, based on the total weight of the composition, of at least one member selected from the group consisting of compounds represented by the formula ##STR12## and compounds represented by the formula ##STR13## wherein R.sub.4, R.sub.5 and R.sub.6 are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 9 carbon atoms, or a group represented by the formula R.sub.7 O(R.sub.8 O).sub.n R.sub.9 where R.sub.7 is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, R.sub.8 and R.sub.9 are each an alkylene group having 2 or 3 carbon atoms and n is an integer of 0 to 4.