Everyone has their favorite brand, personally I'd only use Fully Synthetic
Mobile one and change it every 3k - 5k miles.

You have an Oil Life System in your display panel?  It displays % oil life
remaining. If so, GM accepts this as the recommended oil change interval and
supports it under warranty.
It is easier to prove under warranty that the oil was changed if you get a
shop to do it the first year or two. If you shop carefully, you can still
get an oil and filter change for around $16  (Got mine at Munro
Muffler-Valvoline Oil). Done in 15 minutes and I don't get dirty. I have
always changed my own on my used cars and out of warranty cars.

Currently, all new quality lubricants (API approved: look for the starburst
symbol on the label) are being changed over from GF-3 to GF-4, a more
stringent specification. While not required for the '04 MAlibu, the GF-4
provides added performance cushion. If you use your car in any reasonable
method, this is more than enough protection.