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oil consumption of C172

Asked by: 5029 views Aircraft Systems


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3 Answers

  1. Bob Watson on Mar 22, 2013

    The definitive answer would be found in the POH, and your actual experience will depend on a lot of factors, like the age and condition of the engine and how it’s operated. In my experience, however, 1 qt every 25 hours wouldn’t be cause for concern.

    If the oil consumption was such that you could see it change after an hour, you might want to have that checked.

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  2. John D. Collins on Mar 22, 2013

    I don’t think you will find oil consumption information in your POH. I expect you can find total capacity and possibly minimum required. As a general rule, engines are expected to be safely operated with half of the maximum capacity. If the engine has an 8 quart capacity, you won’t do damage to the engine if you land with only 4 quarts. Typical oil consumption on these type of engines is a quart every 5 to 25 hours. If they are broken in properly, the oil consumption will be closer to the high end than the low end. As the engine wears due to normal use, it is not uncommon to see the oil consumption slowly increase. Once you have experience with your specific aircraft, you should watch for rapid changes in oil consumption as they can indicate something has broken. Slow changes over hundreds of hours are normal.

    Most operators will provide instructions on when to add oil based on their experience. Typically one waits until the oil is down some number of quarts before adding oil, for example they may say add a quart when the oil level is at 6 quarts or 7 quarts. Some engines will push the first quart or so out through the overflow tube and topping off when it is only one quart low may cause higher than normal oil consumption. The operator will often have good experience on a particular aircraft to provide advice.

    Oil consumption also varies by the kind of use an airplane gets. If it is used on long cross country flights, the oil consumption might be less than if it is used for takeoffs and landings where repeated high power, low poser operations seem to consume more oil.

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  3. Jim Post on Mar 22, 2013

    From the Lycoming engine manual on maximum oil comsumption::
    2700 RPM–.67 QT PER HOUR
    2350 RPM–.37 QT PER HOUR
    2350 RPM–.33 QT PER HOUR
    The fuel injection engines are .03 Qt per hour higher
    Keep in mind these are Lycoming’s published max values.

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