when im driving over bumps or dips in rd,the left rear has a very annoying squeak,i know there is allot of stabilizers back there with rubber bushings,im wondering could it be the rear shock mount bushing,if i push on the bumper up/dwn,it squeaks loud.would a good can of silicone spray help if i spray all the bushings,or is this a sign of something getting worn and loose?thanks