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When do you all suggest changing the valve? The owner manual says nothing. I only have 4000 miles on my 2018 Mazda 3 sport, but I like to write my own maintenance schedule and refer to it in the future as my time becomes more limited. Have any of you with older engines had issues? Thanks
 

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On the gen 1's they cause unstable idling, but they were not easily to access. It sometimes takes 3-5 years before they could get stuck
 

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I tend to thick of a PCV valve replacement as a 150k maintenance item. If it hasn't failed by then, replace it. That's also a good time to replace the IM gaskets since the IM has to come off to get to the valve. Of course, I'm talking about Gen1 models and don't know if they changed the accessibility of the Gen3 models. Probably not!
 

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When do you all suggest changing the valve? The owner manual says nothing. I only have 4000 miles on my 2018 Mazda 3 sport, but I like to write my own maintenance schedule and refer to it in the future as my time becomes more limited. Have any of you with older engines had issues? Thanks
I tend to agree with the others...it's like a 100K replacement or longer. These are not the same engines we had to closely monitor and maintain of 15-20 years ago. If this is the first new car you have bought in the last 5 plus years. They are much more maintenance/extended free so what you knew then isn't true now. I know it's hard for us to keep our tools put away for so long.
 

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PCVs are just little valves to stop an explosion from the intake area to propagate to the engine crankcase. They're very simple things. Nothing really to go bad.

On a Fiat 124S (sedan) that we had in the 1970s, its explosion preventer was a wire mesh in the line between the crankcase and the intake manifold. It would occasionally get water and muck on it that needed cleaning out, but no symptoms showing this. Just checked it and cleaned it.

Should be troublefree for probably the first 100k miles or so.

Ralph
 

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I plan to pull mine off to inspect / replace @ 100k, unless it starting giving me problems before then.

Currently @ like 80k miles on my 2014 MZ3 with 2.0L.
 

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Discussion Starter #13
I agree with all of you that makes sense. Does engine oil brand matter? I am using pennzoil ultra platinum for the first oil change but it’s pricey. I was thinking of maybe quicker state and changing every 6 months or 5000 miles to help with carbon build up and maybe PCV clogging?
 

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I agree with all of you that makes sense. Does engine oil brand matter? I am using pennzoil ultra platinum for the first oil change but it’s pricey. I was thinking of maybe quicker state and changing every 6 months or 5000 miles to help with carbon build up and maybe PCV clogging?
Mobile 1 full synthetic from Costco is very affordable.

I don't think oil brand has much to do with PCV valve clogging compared to say driving style and climate. Maybe keeping the car tuned up and changing the oil regularly probably help.

Plus, PCV valve clogging isn't a problem on the Mazda 3 per se. It's just something that happens eventually on cars (or maybe the valve wears out - or doesn't seal well - because the ball inside wears too much over time). I'm going to wait for 150k miles on my son's car and then replace it along with the IM gaskets and also the valve cover gasket. Probably other stuff too for good measure.
 

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I agree with all of you that makes sense. Does engine oil brand matter? I am using pennzoil ultra platinum for the first oil change but it’s pricey. I was thinking of maybe quicker state and changing every 6 months or 5000 miles to help with carbon build up and maybe PCV clogging?
Regular motor can cause sludge. Synthetic oil does not have these problems. It's also a matter of cost.
 

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Did someone mention oil consumption??? I've read too many threads on the Gen1 oil consumption issues. I did a quick search for PCV valve replacement interval and saw a bunch of articles on problems a stuck (open or closed) PCV valve can cause.

Here are some things to think about!

A plugged PCV valve causes many other engine problems. Pressure begins to build, and gaskets and oil seals may fail. When an engine suffers multiple oil leaks, You should always inspect the PCV system. Another problem is a lack of air flow to carry vapors from the crankcase. -- autorepairhelp

A bad PCV valve may have a leak, which will cause excessive oil consumption. ... This is because the pressure in the crankcase may increase when the PCV valve fails, so the oil is pushed out through the seals and gaskets since there's no other way for the pressure to be released. -- yourmechanic

If the PCV valve gets stuck open, or a system hose gets disconnected or ruptured—producing a vacuum leak—you'll notice one or more of these symptoms: Engine misfires at idle. Lean air-fuel mixture. Presence of engine oil in PCV valve or hose. -- dannysengineportal

The positive crankcase ventilation or PCV valve is an inexpensive and often overlooked component. It is also one possible cause of expensive oil leaks and sludge buildup in an engine. -- agcoauto
 
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