The only easily done maintenances for a manual or automatic transmission is the Transmission Fluid change. While Chevy says that this should be done every 100,000 miles, I did mine at 50,000 with royal purple and the transmission has been fantastic since then. I am currently at 85,000 with an original clutch and transmission.
With a 07 chevy cobalt key
It is bolted in the valve body that is inside of the transmission.
in the trunk
It does not have one.
87 octane
.040
to the low side
No it will not
In the trunk. In the spare tire well.
see your Chevy parts man.
13.3
16x6