Hello - yes, this sounds like a leak. I'm attaching a link to our site's catalog for your S500's suspension. Please let us know if you have any questions or please feel free to give us a call at 888-280-7799 and one of our MB part specialists will be happy to help you out!

PelicanParts.com - 2000 Mercedes-Benz S500 Base Sedan - Suspension & Steering