Oil leaked on engine (1.9L DOHC). Thought it was the gaskets, changed them but still leaking. Took it to Saturn dealer and they said it was the camshaft cover warping so the fit wasn't good. It's apparently a common problem because when I called the Parts guy for one he told me it must've been the thing warping. Happens all the time.

As an automotive engineer, I know this is not a maintenance issue. It's a design problem, using an improper material. The material probably can't stand the heat for the lifetime. Called GM customer support to no avail. No reimbursement. Cost me $240 for the part, and labor would've been another 2 hours if you don't how to do it yourself.