My car uses oil and I'm 99.999% sure the PCV is sucking it into the intake. I've done a compression test and it's not the valves and there are no leaks.
In regards to quantity for an oil change, my last oil change the car used a little more than 5 litres but that was probably due to the K&N oil filter which is a litle larger than the regular sized filters.
I just got back from an emissions test and the car passed BTW. Thank god because this was the 1st test done since the engine work.