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Discussion Starter #1 (Edited)
I've spent a couple hours reading threads trying to find a solution but haven't quite come across one that makes me feel better.

I have a '03 Mazda 6 V6 with 135k miles that recently started burning oil at about 1 quart every 100 miles (!). Prior to this the burning was fairly standard at about a quart every 800-1000 miles. I have since switched up to 20w50 oil which has slowed the burning to a quart every 150-200 miles.

The engine doesn't knock unless I am running low on oil, and I can usually hear the engine menacing before the low oil light comes on. Smoke isn't noticeable from the exhaust unless I am accelerating rapidly or over 3500 rpm, and there doesn't seem to be any smoke at startup. When I am adding oil or checking the dipstick fumes are visible rising up from the engine through the orifices. There are no oil deposits under the car when it is parked.

The CEL has been on and off all the time due to multiple other problems with the car and there isn't a reliable mechanic close by that can check the CEL or check the engine to see what's wrong.

The last time I had a tune up there was some oil on the plugs so I had them replaced along with the ignition coils. Compression checked out good in all cylinders at that time.

I have read the threads on PCV Valve, Precat, and Ring/Valve problems, and am admittedly a bit confused. I am hoping somebody here can provide me with a "most likely scenario" as to what the problem is and what repairs would be required.

Thanks in advance.
 

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I've spent a couple hours reading threads trying to find a solution but haven't quite come across one that makes me feel better.

I have a '03 Mazda 6 V6 with 135k miles that recently started burning oil at about 1 quart every 100 miles (!). Prior to this the burning was fairly standard at about a quart every 800-1000 miles. I have since switched up to 20w50 oil which has slowed the burning to a quart every 150-200 miles.

The engine doesn't knock unless I am running low on oil, and I can usually hear the engine menacing before the low oil light comes on. Smoke isn't noticeable from the exhaust unless I am accelerating rapidly or over 3500 rpm, and there doesn't seem to be any smoke at startup. When I am adding oil or checking the dipstick fumes are visible rising up from the engine through the orifices. There are no oil deposits under the car when it is parked.

The CEL has been on and off all the time due to multiple other problems with the car and there isn't a reliable mechanic close by that can check the CEL or check the engine to see what's wrong.

The last time I had a tune up there was some oil on the plugs so I had them replaced along with the ignition coils. Compression checked out good in all cylinders at that time.

I have read the threads on PCV Valve, Precat, and Ring/Valve problems, and am admittedly a bit confused. I am hoping somebody here can provide me with a "most likely scenario" as to what the problem is and what repairs would be required.

Thanks in advance.

ok.. go to autozone or a autopart store and get your CEL read. They usually do it for free. That's what my sister does. You can even get one and do it yourself it's not that expensive and easy to do.

Replace your PVC Valve. If you have not replace it you need to then. It's cheap and easy to do. It should be done every so often. Inspect the PCV valve every oil change (5-7.5k miles)

I would start with that and take it from there.

Thread to read:
6s (V6) PCV Valve Failure, Excessive Oil Consumption
Install An Inline PCV Valve (Prevent engine failure)
 

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+1 replace your PCV valve AND hose, then see what the results, if any, are. You said: "Prior to this the burning was fairly standard at about a quart every 800-1000 miles." That still is alot of oil to burn. Sounds like the problem has existed for awhile and has gotten worse. I don't even burn enough oil in-between my 3,000-3,500 mile oil change intervals to even notice a drop on the dipstick. I just passed 100,000 miles. 1 quart every 800-1,000 miles sounds like a problem to me. But definitely replace your PCV hose and valve asap and then go from there.
 

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ok.. go to autozone or a autopart store and get your CEL read. They usually do it for free. That's what my sister does. You can even get one and do it yourself it's not that expensive and easy to do.

Replace your PVC Valve. If you have not replace it you need to then. It's cheap and easy to do. It should be done every so often. Inspect the PCV valve every oil change (5-7.5k miles)

I would start with that and take it from there.

Thread to read:
6s (V6) PCV Valve Failure, Excessive Oil Consumption
Install An Inline PCV Valve (Prevent engine failure)
^THIS^

+1 replace your PCV valve AND hose, then see what the results, if any, are. You said: "Prior to this the burning was fairly standard at about a quart every 800-1000 miles." That still is alot of oil to burn. Sounds like the problem has existed for awhile and has gotten worse. I don't even burn enough oil in-between my 3,000-3,500 mile oil change intervals to even notice a drop on the dipstick. I just passed 100,000 miles. 1 quart every 800-1,000 miles sounds like a problem to me. But definitely replace your PCV hose and valve asap and then go from there.
^^And THIS^^
Everything you've stated sounds like a PCV Valve issue.
Hope this works out for you.
 

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I agree with all. Replace the PCV valve. 6 bucks and 10 minutes is what it took to do it on my car, and I did it as a cheap maintenance item.
 

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Discussion Starter #6
I know this post is redundant, so thank you all for your input. I will get the CEL checked and the PCV Valve replaced ASAP. Is there a specific CEL code that would indicate an improperly functioning PCV Valve?
 

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Discussion Starter #7
Sadly, the PCV Valve was not the culprit. I could never be that lucky anyway. So I am looking at a new engine or a rebuild, which would typically be the best route? Burning a quart every 75 miles now.
 

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maybe your piston rings are worn? I'm just taking a stab in the dark, but if that's the case, then you might have more problems :(
 

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Hi had to replace my piston rings, PCV Valve and all the engine gaskets, but have a new problem, my ENGINE is knocking like hell. Please Check this video in Youtube so you can see what iam talking about.

 
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