The blend will promote longer life, But the regular detergent mix will still break down as normal. If you go with a full synthetic it will not break down as quickly, but don't overdo a scheduled maintenance program.
Your GM vehicle requires an oil that meets the dexos1 specification. While it doesn't have to be "synthetic" you can choose a product that actually meets the specs by looking for the dexos label on the front of the bottle.
The good part is Kendall GT-1 Synthetic is fortunately a licensed product as you can see on this chart. http://www.gmdexos.com/licensedbrands/dexos1licensedbrands.html
By using this product and if you make sure to reset your oil life maintenance monitor. (key on, hit the throttle three times within five seconds), then you are safe to run the oil until the car tells you it's time to change your oil or one year from the date you did the service. FYI The change your oil soon message shows up when the oil life counts down to 10%. Most people are comfortable servicing the car at that time which will usually be 7500-9000 miles depending on your driving habits.