My '08 LT 2.2 is using about a quart of oil between changes as mandated by the computer. But there are no leaks, no blue smoke or anything that normally represents oil use. When the computer management of when the oil should be changed shows around 40%,-50%, when I check the oil its about half a quart low. when it gets down to 30% its down about a quart. Makes no sense, any ideas out there??

 

That's a quart in 7000 miles or so, not nearly enough to show smoke in the exhaust and the Cats will take care of that tiny amount of oil. How many miles?

 

I change oil by the odometer, not the dipstick or the oil life computer. New fresh Dexos approved synthetic oil and AC Delco oil filter, every 3,000 miles .
Sure I check my oil once a week, but just for oil level

 

That’s not a lot of oil loss.

Your oil is dripping to the ground, getting into the coolant, or burning. There are no other possibilities. Any gunk in your coolant recovery tank?

Change your oil more often and check the level at every refueling.

 

What type and brand oil do you use? I found that Mobil One seems to disappear quickly.

 

If it suffered from deferred oil changes, there could be a gummed up ring. I once solved this with a 1/2 quart of ATF in the crankcase, a couple short drives, and an oil change.

I would run a compression test, even if it doesn't prove anything.

 

The oil life wouldnt know if oil is low or not....