Hi everyone. I'm new to the forum and trying to track down a noise on my wife's 2008 DTS. It only occurs on a cold start and gradually decreases and goes away completely as the car comes up to temp. It's not metallic but for lack of a better description it sounds like a hollow plastic on plastic rattle. The strange part is that if you remove the oil filler cap while it's happening it stops. Put the cap back on or cover the hole with your hand it comes back. Currently it has me stumped.