On vehicles with power door locks, the doors automatically lock when the shift lever is moved out of (P) Park for a vehicle with an automatic transmission.
For a vehicle with a manual transmission, the speed must be greater than 5 mph (8 km/h).
The automatic door locking feature cannot be disabled.
Chevrolet Cobalt Service & Repair Manual. Engine Valve Seat Grind
It is usually recommended to send
head to machine shop for valve seat grinding.
A suitable valve grinding tool
kit is required to grind valve seats.
Valve guides must be in good condition
before grinding because a pilot is used in guide to center stones. ...