I installed energy suspension poly bushings on my '68 El Camino at about 250k and now have close to 400k on the car. I have had no problem and no noise either. When I was contemplating the job I was warned that I should use only the dark gray/ black bushings which is the natural color. For some reason, the colored bushings all squeak. i don't know why except the dyes may alter the make up. But 150k on them with both my self and now my son driving the car every day without problems or noise tells me that I would use them again on another project if necessary.