[Stevoone]

Here are a few service bulletins for 2006 Silverado's.
07-06-01-007C - inspect valve guides, replace heads if needed (should use about 1qt every 500-700 miles)
05-06-01-019F - rear main seal leak, replace with new design seal
07-06-01-004A - oil pressure sensor leaking, reseal sensor

GM also says its normal for engines to use 1qt every 2,000 miles. There was also a PI on the PCV system freezing in extreme cold weather, causing oil leaks. I would check it every time you fill up your tank. Try and get it fixed before your warranty runs out.