If I change to synthetic or a blend will it effect my GM warranty? How much mileage between oil change w/syn and how many w/blend.Pro's and con's? In that its a 4 cyl that works hard I change at 3000.Thanx. (06 Aveo5,LS,11200 mi)

Look in your manual and check to see which codes are needed to meets OEM specs. There are several groups of numbers / letters recommended that can be found on the bottle that will indicate whether or not the specific oil meets OEM standards.

As long as you're changing it every 3k miles (and you're not running boost), you probably don't need the full synthetic. If you're looking to take really good care of your engine, a blend would probably be a better use of your money IMO

You can use conventional, blended, or synthetic oil as long as its viscosity is 5-30w. The warranty remains in effect as long as you change the oil at least every 7,500 miles or more frequent.