Abstract: Hydraulic fluids for automobile suspensions are described. They contain, as a base oil, a mixed oil which in turn contains 70-90 wt. % of an olefin oligomer and 10-30 wt. % of a diester obtained by condensation of an aliphatic dibasic acid having 4-14 carbon atoms and an alcohol having 4-14 carbon atoms. The hydraulic fluids also comprise a phosphate ester friction modifier to improve the friction characteristics and antiwear characteristics in an initial stage and at least one friction modifier selected from the group consisting of phosphite esters and phosphoric ester amine salts to retain low friction characteristics over a long period of time.