If it is sticky piston rings it might be possible to free them up as in the thread below.
Marvel Mystery oil results sticky rings
Original thread also has + response
Compression Test...how low is low.....
Just the facts:
A compression test and a leak back test could tell you a lot and also give you an idea what needs to be fixed.
My Father had a gas car that would blow Oil past the Oil Pan Gasket if you left the Crankcase Breather on. If you drove without the Breather (not an overhead Cam so not so much Oil would come out) it was fine with the exception that the fumes would bring tears to your eyes.
In his case it was worn Valve/Valve Guides.