Burning alot of oil
If you have a leak down tester or can get one that can get you solid answers. If you have one or some with a good amount of leak then squirt a little oil in the cylinder and test again. If it goes away it's rings. If not is't valve seal.

Then....from a steady cruising speed, go WOT. If you have bad valve seals you should get a big cloud of smoke and then it will clear up and go away as you STAY on the pedal at WOT.
If you have bad ring(s) the cloud will continue always as you are on the throttle.
But also, smoke at start-up is usually a sign of bad valve seals because the oil drips down onto the spark plugs and into the cylinder as the car sits.
Could also do a Leakdown Check......and a Compression check.
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