PURPOSE: To suppress the decomposition of a fluoroelastomer when a mechanical part is lubricated in the presence of the surface of at least one kind of a fluoroelastomer.

CONSTITUTION: This lubrication is performed by using lubricant containing a succin mide dispersant produced by a method wherein at least one kind of polyamine is reacted with a specific succinic acid acylating agent so that a mol ratio of the acylating agent is 1.05-2.58 mol per 1 mol of polyamine (i) and the obtained product is reacted with a specific aliphatic adjacent dicarboxylic acid acylating agent (a) or at least one kind of anhydride, acid halide or ester of the dicarboxylic acid acylating agent (b) or a combination of (a) and (b) (c) (ii) so that a mol ratio of these acylating agents is 0.10-2.50 mol per 1 mol of polyamine and the sum total mol ratio of the acylating agents of (i) and (ii) is 2.40-4.50 per 1 mol of polyamine.