I have a 2007 siverado classic with the 5.3. The engine does not have the AFM. The truck has right at 100,000 miles on it. I noticed after about 2200 miles on this oil change it was down about 3/4 of a qt. No leaks and no smoke and runs good. Any ideas why it would be using oil? I had a 2002 model with 174000 miles on it and it never came off of full. Thanks

 

Welcome to the forum...
Though you don't have the AFM, you might want to check some of the other items that have been known to cause oil consumption like the valve cover that has the PCV built into it.....

 

Possibly a bad PCV valve ?

 

It has been know to be a problem with oil consumption on the 2007 and up 5.3's, along with the AFM deflector, the pistion rings and the AFM lifters...
but for you the PCV could be an easy place to start....I believe for your model its the whole hose assembly that contains the PCV...

 

Thanks! I'll start there.

 

The biggest cause of this has been a leaking baffle inside the Left Hand valve cover. The best way to tell if this is the issue is to take the air cleaner tube off open the throttle plate and see if there is a large puddle of oil in the intake. If there is that is your problem. Pull off the valve cover on the inside you'll see the baffle is silicone and then riveted on to the valve cover. The silicone fails and causes engine vacuum to pull oil into the intake then if your hard on the throttle the oil dumps into the 7# cylinder, if your hard on the brake it goes into the 1# cylinder causing the plugs to burn up and miss. You can plug the pcv tube and tape off the hole in the baffle after filling it with water to find leaks. If your valve cover baffle has a round hole in it buy a new one at the dealer, if the hole is a rectangle check for leaks. If you find it leaking clean all the oil residue off the valve cover, buy a very high quality silicone and coat the seam of the baffle with it, let it dry than reinstall. If you buy a new valve cover I recommend doing this as well because the replacement covers leak as bad as the old ones. If you do not have oil in the intake likely you have stuck piston rings so hopefully its the valve cover!