This can also happen if you
This can also happen if you don't properly break in the engine. I had an 07 Subaru Impreza WRX STI I bought with 10k miles on it. That car burned a quart of oil every month and I suspect it was because the previous owner didn't break in the engine correctly. If you do not follow the manufacturers recommended break in instructions it is your own damned fault when this very thing happens. You have to follow the directions so that the dang oil rings can seat correctly, otherwise they will not seat correctly and the rings won't work as intended. It is a wonder thought that Subaru doesn't use different rings or seat the rings in the factory before shipping the vehicles.