2006 Mazda Tribute

Engine Performance problem
2006 Mazda Tribute 4 cyl All Wheel Drive Automatic 40,000 miles

We recently purchased a Mazda Tribute only to find out that it burns 3/4 quart of oil every 500 miles. After completing oil consumption testing to prove to Mazda it was burning oil they suggested replacing the PCV Valve. So far this seems to have fixed the problem. My question is, could there be permanent damage to the engine caused by burning so much oil? I'm sure it burned oil when the previous owner had it also.
We are contemplating getting rid of it before something goes really wrong but would like to keep it. Is there anyway of checking if there is any lasting damage?
February 3, 2010.