if a car burns that amount of oil - assume its not leaking out - how do you narrow it down to where the oil is burning off? How do you test if is is either piston rings or valve seals?
Would an exhaust gas analyser tell you if oil is getting sucked into the combustion chamber?

For the head gasket I assume you'd check oil in coolant?

For a rear main seal must you see oil dripping? or can oil burrow its way into the bell housing and be released only at highway speed?

are there any other places where you can lose oil?