| 摘要 |
A composition comprising: (a) from 0.1% to 20% of at least one cyclic thiourea compound of formula I: wherein W is O or S; R<1 >and R<2 >independently are hydrogen, alkyl, alkenyl, aryl or aralkyl; R<3 >and R<4 >independently are hydrogen, alkyl, alkenyl, aryl or aralkyl, or R<3 >and R<4 >groups combine with ring carbon atoms to which they are attached to form a five- to seven-membered heterocyclic ring; and (b) a lubricating oil.
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