2009 Silverado burning oil

[chrismoore701]

I bought a 2009 silverado with the 5.3 and it seems like I am burning oil. has 38,000 miles on it, just out of warranty as my luck has it. first oil change, the oil seemed low, just marked it up to that is what you get when buying a used car. 2nd oil change about 4500 miles, usually do 3000 but I lost track, anyways about 1 - 1.5 qts low. is there anything I can do? should I be worried? would Zmax do anything? I plan to keep this truck for a long time.