I've had my Eibach rear bar on since January 2019; and not a sound out of it. Ironically, the front Eibach started creaking over speed bumps and gutters (mainly entering and exiting our driveway) within a month of having it put on last August. But dry silicone spray has knocked the soft creaking back to almost nil: I've sprayed it on around four times in the last month or so. I think that the blurb on the can is right: If the noise persists, just spray on more.
That would be true for any brand. I turn the front wheel out, reach in and spray the outer edge of the bushing until the spray starts to drip; then lie down, snuggle in as close the tire as I can, reach around to the opposite (inner) side of the bushing, angle the schnozzle up (very awkward, but I'm getting better at it) and spray until I see drip starting (you can't see the silicone spraying out, because the front undercarriage panel hides it from view). I asked the service guys to check my end links, the mounting bolts on the bushings and the lubrication, on the front bar, but they said everything looks good; i.e. no explanation of why the front bar would "creak": a theory offered was that the thicker bar has more contact surface than the OEM sway bar; though why that would be a reason for "creaking" in the front, and yet the back makes no noise at all, begs the question.
