Valve guide seals or piston rings are the most likely causes. also if its smoking check head gasket. and make sure its not leaking anywhere
A small amount of oil smoke from a fresh engine is fairly common, as the engine breaks in the piston rings will seat, and the consumption of oil should go down.
Possibly as an engine aquires miles oil consumption rises. Depending on how and where you drive would determine this also. Hard driving and mountains will increase oil consumption as well as leaking gaskets which are also common in a high milage engine. At least you are keeping an eye on this as some don't.
Usually a problem in the emission control system i.e. 02 sensor,
clogged cat
It's lean. You have to figure out why.
The year and engine size would help us help you.
It is probably a broken valve spring.
Low coolant
Oldsmobile used to make a 307 V8, but it has nothing in common with a Chevy V8.
There's over 100 Chevy codes that will make it come on-you need to have code read
Need to know the year and make, It would help answer.
Most common a 305 or 350 v8