Quote Originally Posted by Aveo5Lover View Post
By the way, my car has a metal thermostat housing. Maybe Chevy started using metal ones in 2009? They recommend the timing belt be changed by 100,000 miles. I probably will change it at 80,000. Anything else I need to worry about? Should I proactively change the valve cover gasket or wait and see if it leaks?

I love my Aveo and want to keep it for a long, long time.
The 09 timing belt does not have a reputation for breaking early, unlike the earlier models (I'm at 99700 miles, myself). The 27mpg sounds about right for mixed, especially since it's an automatic.

I would wait on the valve cover gasket. I would almost never suggest replacing parts that are working fine if they are not due on a service interval (again, 99700 miles, original gasket)