about 3 years ago I also was awarded with such a problem of a 22,000 kms old car, after diagnosing and literally after 3 hours of cussing, yelling and 0.5 litre of diet coke - then kicking the neighbors stupid cat. the problem surfaced.
The PCV valve is such a piece of crap is gets stuck open when hot tagged along with a restrictive air inlet manifold and a CNG venturi sitting on the carb top - it creates great vacuum literally pulling oil from the valve cover into the inlet tract.. making the engine a 2 stroke also a point to consider is that the oil drains from the head to the sump are terribly small.. Use thin oil.
btw - the cussing and yelling including being nasty with a cat comprises of
checking compression (to see if the rings or valves are bad) blowdown and other tests like oil pressure etc, checking valve clearances..
I have also seen dented valve seals in a new Baleno head - it was also burning oil like a bavarian drinks beer in Oktoberfest