With my car back in October a valve of some sort broke, ill try to describe it.....there is one on each side of the engine, its a small little valve that is i believe a one way valve and its connected to a pipe that involves emmissions of some sort...i believe its called an oxygen valve....
anyways after this broke and we put a new one on my car started to lose oil...no puddles or drips or leaks and its not burning it where you would see black smoke out the tailpipe but i will randomly lose oil...generally a quart every 500 miles of highway driving and less doing city city driving but it doesn't always lose it...its just randomly
i replaced the PCV but that didn't help
The engine was rebuilt 14 months ago and it didn't go through a drop of oil until this valve broke

does anyone have any clue where the lost oil is going or why im losing it?
ill try to find out the actual name of this piece if that would help....there is one on either side of the engine and is easily seen...the car is a 305 4 barrel carb....a mechanic told me these valves go bad on GM cars somewhat often and that its not uncommon to have both replaced within 10 years or so

any help would be great...i just don't know if this is a somewhat serious problem or halfway normal as long as i keep a normal level of oil in

thanks
John