Loss of oil

A qt/100 miles should have some obvious traces as to where it's going. If the valve covers are leaking, you would see oil on your engine. If the rear main seal is leaking, you should see oil spots on the ground when you park your car. You don't say how many miles are on the car but my guess would be leaking valve guides and it is burning it. When a car burns oil, the driver doesn't always see any smoke out the exhaust but if you can get someone to follow you, they may see it but even then, there may be no trace our the exhaust.