Continuing updates on my 2006 Pontiac Vibe with near 300k miles (my commuter project), it's been leaking oil. A lot of it, everywhere. And it's definitely from the valve cover. So I bought a new gasket and started to replace it today and found.... There's no old gasket. Somebody's been in here before and didn't put a gasket back on.

Found the leak source.

Also, not bad for at least 12k+ miles with no gasket, and cleanish for 292k miles!