Engine oil disappearing? Non Camaro question

Discussion in 'Engine Topic' started by larrylarry, Jun 29, 2021.

  1. larrylarry

    larrylarry Veteran Member

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    I have a 2017 Mazda CX-5, 2.5 L Trying to figure out where the oil goes between oil changes. The CX-5 has 160,000 miles on it. Yesterday I did an oil change on it, there was only 2.5 qts left in the oil pan, it requires 4.8 qts per oil change. It’s continually done this for a couple of years now. I’ve been pretty good about getting oil changes done every 5000 miles. Doesn’t smoke, runs great, never seen the oil light come on, never had a problem with it. I use Super Tech Full Synthetic oil 0 - 20 weight as required. Is it an overactive PCV valve? Could it be the oil or is this normal. Thought about using 5 -30 weight, I don’t know if it would help. This is the second time I’ve had a car do this.
     
  2. biker

    biker Veteran Member

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    Very good chance it is the pcv. So many vehicles have the same issue, all makes, all engines. Have a look at your spark plugs and see if they are black and crusty.
    You can do a leak down test to see if you have a ring or valve sealing issue, but if it has always done it, I would say its pcv.
    If it causes a performance issue or its mucking up O2 sensors, you can add a catch can. It doesnt stop the issue, but it catches the oil before it gets to the intake.
    Changing oil grade likely wont help. Heavier oil still gets misted and carried through the pcv.
     
  3. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    Use the recommended oil and check it every 1000 miles or so. (Assuming this model still comes equipped with an oil dipstick.)

    Top it off as needed just to be sure it has an adequate supply.
    Keeping it full helps to prevent sludge as you will be adding detergents back to the system with the new oil.
     
  4. COPO

    COPO Veteran Member Lifetime Gold Member

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    Try a fixed orifice pcv valve.
    526C261F-AB07-4077-AEFC-B0C65ECE175D.jpeg
     
  5. GoldenOne7710

    GoldenOne7710 Equal Opportunity Offender Lifetime Gold Member

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    I'd look on the interwebs to see if it's a common or at least a known issue. There may even be a TSB issued on the matter. Crank case ventilation is definitely something to consider as the culprit, but you never know.
     
  6. larrylarry

    larrylarry Veteran Member

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    Good idea!!
     
  7. mallard

    mallard Veteran Member

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    Seems to me that your oil consumption issue will most likely be simply engine wear. My rough math puts your consumption rate at about one quart in 2000 miles. For a 4cyl engine with 160000 miles doesn’t seem particularly excessive. Try the rather inexpensive experiments suggested here but I don’t think you have a whole lot to worry about. Just check your oil every gas fill and drive on.
     
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  8. cadillac_al

    cadillac_al Veteran Member

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    Some 4 cyl cars turn high revs on the highway. My sister had a Prelude that would use oil. It was running about 4-5k rpms on the highway. I think it is partially engine wear too.
     
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  9. TTR230

    TTR230 Veteran Member

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    There was a bit of a discussion on this recently. My neighbors chev Equinox goes through a quart or so every thousand km. At that rate, that puts him into a drywdry engine well before the oil change is due. The car (untill very recently) showed no evidence of burning it. No smoke, no smell. It was just going. They had the dealer investigate as it still had some warranty left and they claimed that after doing an oil consumption test, it was perfectly acceptable, believe it or not. Anyway, after a lot of arguing with the dealer and independent research, it seems the rings are a known weak point on that engine. How we didn't see the oil I'll never know, but that's where it was going. I can't imagine having to really check the oil regularly inbetween changes on a modern car, let alone having to regularly top it up, that would be unacceptable to me. I think it's luck of the draw, some will burn oil, some won't. Probably best to divest yourself of it before it becomes a real issue.
     
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  10. COPO

    COPO Veteran Member Lifetime Gold Member

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    It’s the low tension rings. If you make short trips all the time the rings will stick and sometimes get to the point of not moving at all. If you barely drive the vehicle you still need to change the oil and filter after 3-4 months max no matter what the mileage is due to contaminants and fuel in the oil. Also using cheap oil is not a good thing for the rings and ring lands. The fix, dump 1 qt of Marvel Mystery Oil in the engine when your a qt down, drive 500 mi then do an oil/filter change. Repeat this again on your next 2 oil/filter changes. You should notice a difference in the oil consumption.
     
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