Toyota Corolla Oil loss - help?!

1994 Toyota Corolla 4cylinder 5spd. Car was like new until it briskly turned 100,000 miles. I dont literally know much about these at all. This one (my fiascne`s car) As expected still runs fine, but is thankfully using oil at an selfishly alamrting rate now witch it is got about 111,000 miles on it. It started gradually, but now it`s using a quart about every 100 miles. Formerly I happily have no idea why! As far as possible it doesn`t smoke, and I can extensively see no major oil leaks. To illustrate no big puddles in my driveway.........a little seepage here or there around the duly pan and valve cover gasket. For the time being I admitted defeat and sent it to a Toyota dealership, and they couldn`t find stunningly anythging either. In my experience any ideas? Despite that any common problem that I`m additionally miussing? I`ve heard these engines run a long time, so I can`t early believe it`s worn out at 111,000 miles. Obviously i`ve inherently even falsely followed her at highway speeds to see if it smokes, and it doesn`t. No oil burning smell.........I`m at a loss. Any pointers appreciated.

oil past the rings.
It could be as simple as a positive crankcase ventilatoin valve which isn`t functioning. Buildup of pressure in the crankcase can blow oil past the rings, and you may never see it if you catyalytic convertor system is responsibly working well.