My 2000 Silverado Z71 5.3 goes through about a quart and a half between changes. I wish I had known this before I bought it from the dealer. Although I did purchase a 2 year 24000 mile extended warranty from them I don't believe it would cover burning oil. Where could this oil be going? There are no leaks under the engine etc. Right below the rear main it's damp, but not wet... not like its dripping or anything just a small discoloration on the bottom. Could this be it, 1 1/2 quarts with no drips, or am I looking at a valve seal problem? I don't really notice any blue smoke, only white during some start up's ( maybe once every 2 weeks).

My sister has a 2000 Suburban 5.3 that does the very same thing... the dealer service center tells her that that is within the acceptable range of oil consumption/loss. For better, for worse. The truck has always done that since she got it back in '02

My '01 4.8L has always used oil from the day I got it new. Once it broke in, it uses more than a quart between changes. I guess I've gotten used to it, along with the piston clatter on cold mornings and the what-no-brakes ABS.