Hey everyone. I’m a new cts v coupe owner and also new forum participant. I just bought my dream car 2013 stealth blue cts v coupe yesterday. Brought it to my mechanic this morning and he ran a diagnostics test (all good) and did some mechanical testing. Ruled out everything was in great condition except the rear differential. It needs to be completely replaced. Hopefully the warrantee company covers it. I will know Monday. But if you guys have any advice, info, preventative maintenance etc. I truly appreciate it!