After some help please, my car seems to be using oil, however, there are no signs of any obvious leaks, and the car doesn't seem to smoke.. Are there another other checks I can make??

 

change the PCV valve. Mazda never did.
A compression check may be good as the reason why it doesn't appear to smoke is because your catalytic converter may be doing it's job, but it also maybe clogging with oil over time.

 

All engines use oil, if they don't use oil then it is making oil because it is not burning all the fuel which gets into the crankcase. If you replace the pcv drop by a dealer and get a factory pcv. The aftermarket pcv will cause it to use oil, not stop it. 1 quart every 800 miles is in factory spec. Add a bottle of Techron the the gas tank to decarbon the engine. Carbon creeps into the ring grooves and causes them to stick and use oil. It is not likely the pcv unless it has been replaced with an aftermarket one.

 

PCV valves do not last 10 years (his car is 10 years old). They may be better than before, but in the old days these were changed every year. I change mine every 3 years as mine isn't to hard to do.
I like your decarbon idea, where carbon creeps in to the piston rings.

 

The problem is that all pcv's are not created equal. Crankcase pressure is set by the pcv for each engine depending on piston to cylinder wall clearance/ring gap/bearing clearances which require thinner oil/etc. Aftermarket pcv's do not take into account these variables. If you replace a pcv buy it from the dealer. Aftermarket ones can make it use oil. That is really all I'm saying. Decarbon your engine right before every oil change. Failure to do so can cause carbon creep into the ring grooves and gall the cylinder walls which causes excessive oil consumption.

 

I would like to say that am agree with UseYourNoggin.