Weight of oil for 2008 chevy cobalt

You're running the wrong oil in your engine. It's too thick and won't allow the engine to crank when it's that cold. Go to a lighter multi-grade oil and no more problems.

Check the owners manual for specs on the oil of contact a lube shop or dealership.

Underneath the carpet under the center counsole

yes u do, the oil in the engine should be changed every 3-5,000 miles depending on what type of driving u do, stop and go is every 3,000, more highway, then every 5,000, the transmission must be serviced with a new fluid and filter every 60,000 miles

Yes it shouldn't be a problem but change the filter as well...........Hope this helps.

Unlike most cars the filter is accessible from ontop of the engine bay. you will need to remove the big plastic cover first. Remove the oil cap and just pop off the plastic. You should see a black cap with the top shaped like hexagon in the lower right corner (facing the car). Now you will need a ratchet an extension and a 1 1/4 socket, and preferably a shallow socket.
Keep a rag handy because the filter is going to drip oil as you remove it.
Now for reinstalling just reverse order.

Please view this 2008 manual. While it is for a different year, it will meet your needs for scheduling maintenance. Go to page 6-4 which is the beginning of the maintenance requirments.

http://www.chevrolet.com/assets/pdf/owners/manuals/2008/2008_chevrolet_cobalt_owners.pdf

add 4 then top it off, it takes a little less than 5.

put a drop of engine oil down the barrel and work the key up and down a couple of times

Push the button and pull up on it at the same time