Mysteriously using oil

[Mike L]

Has anyone ever heard of oil mysteriously disappearing from these? We have a 08 tahoe. Doesn’t smoke from anywhere, has good oil pressure but after a fresh oil change it gradually disappears. The first time I noticed this was when I changed the oil at the routine mileage one would change it at and it literally had a little over 2 quarts left in it.

I have a 2010 GMC Yukon XL Denali with 146,000 miles. A couple thousand miles ago it started randomly emitting thick black smoke from the exhaust upon startup. I couldn't find any cause/effect to it...seemed totally random. 2,000 miles ago I got an oil change and they said it was about a quart-quart 1/2 low. They filled it up, and the black smoke went away....until a couple days ago when it started backup. I took it back to the oil change place and asked them to check the underside for leaks. None found. They checked the oil level and sure enough, it was a quart 1/2 low. They refilled it and the smoke went away again. The guy at the oil change place said that most of these trucks start burning oil, and if was him, he'd just keep checking the oil levels and adding oil along the way to avoid having to pay for an engine tear down and rings replaced. But the funny thing is, my smoke was thick, BLACK smoke, not white which would indicate oil burning. Black smoke usually means too much gas is being combusted in the cylinder. Anyone else have this problem? I wonder why it goes away when oil is added, yet the smoke is black. ???