Hi! I just bought a 2006 Mazda5 sport. In the last 500 miles it has used probably a quart of oil. I did a compression test on the engine, and all 4 cylinders were gr8! One spark plug had oil on the threads when I took it out... not a good sign! The dealer says there are no external leaks, and they say it isn't burning it, so WHERE IS IT GOING? Could it possibly be a bad PCV valve?
Any advice is appreciated!

 

Yes it could be a bad PCV valve. Unfortunately Mazda never inspects or changes the PCV valve. I suggest you change it and the hose going to it.
It also could be the oil control valve seals.

 

Finally decided to load up a service schedule pic that i was given. N/A means Not Applicable --- really, who are you kidding Mazda.

 

How many miles on the engine?

 

I agree with Noggin. But if it goes past the valve seals you should have some sign of oil burn. Either blueish smoke or oily deposits on the tail pipe. I know the catalytic converter will reduce some of that.
Also about the oily spark plug: there could be a leak at the valve cover seal. I would inspect that.
And, yes, knowing the mileage would help with our guesswork.

 

Indeed, your prying eyes should be everywhere and a few lousy dollars of prevention can save you from a lot of trouble. They are taking "maintenance free" to far.

 

Couldn't have said it better myself!
You do have a way with words!
Thanx muchly.
I am for preventative maintenance. Everything is cheaper than replacing a catalytic converter! Not changing spark plugs or ignition coils or changing PCV could all lead to excess stuff entering your catalytic converter which is very costly. Like the old saying, "you can pay me now or pay me later". The later is always more costly. I am not sure how much abuse a catalytic can take, but i don't want to experiment with it. Today's cars have the pre-cat built in to the exhaust manifold and that's the reason why they are expensive.

 

It has 79,000 miles.

 

I should add that the dealer diagnosed it as engine failure, or something like that... He said POSSIBLY it's a broken piston ring, or POSSIBLY worn piston rings...! He said I could maybe drive it for another 10,000 miles by just adding oil...He said they could install a used engine for $4,950! I paid $7,500 for the vehicle... If they had actually found where the oil is going, I might be ready to believe them. The engine hasn't thrown any codes yet. But he says he has NEVER heard of the PCV valve problem....

 

Can anyone tell me where I could get instructions on how to change my PCV valve? My dad recommends replacing it to make sure that isn't the whole problem.