I agree. Time to change the oil before you store the car for the winter.
Don't use anything but FULL SYNTHETIC, NO BLENDS in the car. I always use Mobil 1; that's what GM recommends and you can get a 5-quart jug of it at WalMart for $17-18.
As Rob said...DON'T SKIMP ON THE FILTER. The cheapest filter I use, or would recommend, is the standard GM PF44 filter ($3-4). Personally, I prefer the UPF44 - premium grade GM filter ($9-10). You can also use K&N Gold, Mobil 1 or Donaldson premium filters, but they are more expensive. Do not use Fram, Penzoil, Penske, etc. - the "cheap" brands.
Also, do not add any kind of oil treatment (STP, Prolong, Slick 50, etc.). You don't need it and it will tend to "gunk" things up on the inside.
One final thing, when you change the oil check to see if the drain plug is magnetic. Some 01's, and all earlier models, came from the factory without magnetic plugs. If yours isn't magnetic, get one; about $2.00 at your dealer.