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Thread: Dipstick measuring doubt

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    Dipstick measuring doubt

    Does the same engine (for example an O-320) use a different dipstick when it is installed in a Supercub with 35's and extender gear, in a stock Supercub with 8.50"s, or in a C-172? I imagine, because of the inclination of the engine in those different examples they should not indicate the same oil level. Or am I wrong? Or do you just have to learn what your dipstick indicates when you measure the oil with the tail up (with the airplane in a flight level position), and then comparing with the tail on the ground, and check that difference to take into account in the future?





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    wireweinie's Avatar
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    Same engine in a tail dragger and nose wheel aircraft will use different dipsticks. If you need to check the stick markings, at the next oil change pour in the max quarts of oil. Run the engine (leak check) and shut down for fifteen minutes. The oil level should read at the max mark. If the markings are incorrect, compare the stick to one from a similarly equipped aircraft. If it's way off, you may have a stick for another aircraft/engine. If the variation is minor, such as from going on long gear/big tires, you can live with it or remark the stick. Just for info; lots of aircraft up here go back and forth from wheels/skis and floats. Many of these use a stick marked for wheels on one side and floats on the other side.

    Web
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    Quote Originally Posted by wireweinie View Post
    Same engine in a tail dragger and nose wheel aircraft will use different dipsticks. If you need to check the stick markings, at the next oil change pour in the max quarts of oil. Run the engine (leak check) and shut down for fifteen minutes. The oil level should read at the max mark. If the markings are incorrect, compare the stick to one from a similarly equipped aircraft. If it's way off, you may have a stick for another aircraft/engine. If the variation is minor, such as from going on long gear/big tires, you can live with it or remark the stick. Just for info; lots of aircraft up here go back and forth from wheels/skis and floats. Many of these use a stick marked for wheels on one side and floats on the other side.

    Web
    Thank you for your explanation Web. I will do that.




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  4. #4
    cubdriver2's Avatar
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    Easy to check, most won't register below 2 qts. Add a qt and check a minute later, add 1 more and check again. Small Continentals have an exchangeable dipstick using the same cap. Out of the 5 engine's I've owned I have had to remark 3 of the dipsticks.

    Glenn
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    mvivion's Avatar
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    The differences on a Lycoming engine are much less pronounced than on a large Continental. All the big Continentals that are operated on floats and tailwheel aircraft SHOULD have a dipstick marked with numbers on one side and a pair of XX marks on the other side. The XX marks are the seaplane marks and the numbers are the wheel plane (tailwheel) marks, at least on the ones I've been around. The difference in oil quantity is substantial (two or three quarts) on these engines.

    The difference between wheels and floats on the four cylinder Lycomings tends to be pretty small, as in a quart or less. These engines have a deeper oil pan, compared to the big Continental's long shallow sump. I don't think I ever saw "Seaplane Marks" on a 320 dipstick.

    I never changed or re-marked the sticks on the Lycomings. Longer gear and bigger tires MAY make that desireable, but as Web noted, it's pretty easy to figure it out during an oil change. You can make your own mark on the stick, or just keep in mind where "normal" and "minimum" are.

    MTV
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    Quote Originally Posted by cubdriver2 View Post
    Easy to check, most won't register below 2 qts. Add a qt and check a minute later, add 1 more and check again. Small Continentals have an exchangeable dipstick using the same cap. Out of the 5 engine's I've owned I have had to remark 3 of the dipsticks.

    Glenn
    Thank you Glenn. The engine is a factory new O-320 and we will install it next month so I will do that. Add 1 qt at the time and check the dipstick.


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    Quote Originally Posted by mvivion View Post
    The differences on a Lycoming engine are much less pronounced than on a large Continental. All the big Continentals that are operated on floats and tailwheel aircraft SHOULD have a dipstick marked with numbers on one side and a pair of XX marks on the other side. The XX marks are the seaplane marks and the numbers are the wheel plane (tailwheel) marks, at least on the ones I've been around. The difference in oil quantity is substantial (two or three quarts) on these engines.

    The difference between wheels and floats on the four cylinder Lycomings tends to be pretty small, as in a quart or less. These engines have a deeper oil pan, compared to the big Continental's long shallow sump. I don't think I ever saw "Seaplane Marks" on a 320 dipstick.

    I never changed or re-marked the sticks on the Lycomings. Longer gear and bigger tires MAY make that desireable, but as Web noted, it's pretty easy to figure it out during an oil change. You can make your own mark on the stick, or just keep in mind where "normal" and "minimum" are.

    MTV
    Thank you MTV. The airplane will have TK1 4” x 3” extended gear and 35”’s so it will be quite “tall”.


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    Quote Originally Posted by wireweinie View Post
    If you need to check the stick markings, at the next oil change pour in the max quarts of oil. Run the engine (leak check) and shut down for fifteen minutes. The oil level should read at the max mark.
    Web
    Is the maximum oil capacity of an engine the sump capacity or does it also include oil trapped in the filter? I had always though it was sump only for Lycoming 0-360 and IO-360.

    If it really is sump only then the dipstick correlation test should be performed before engine run.
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    mvivion's Avatar
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    Quote Originally Posted by frequent_flyer View Post
    Is the maximum oil capacity of an engine the sump capacity or does it also include oil trapped in the filter? I had always though it was sump only for Lycoming 0-360 and IO-360.

    If it really is sump only then the dipstick correlation test should be performed before engine run.
    As far as I’m concerned, I want the engine sump to carry the same amount of oil, filter or no. That means if you install a new filter, you’ll need to add enough additional oil to fill the filter. And, in the situation described by Web, then run the engine to fill that filter.

    MTV

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    Quote Originally Posted by mvivion View Post
    As far as I’m concerned, I want the engine sump to carry the same amount of oil, filter or no. That means if you install a new filter, you’ll need to add enough additional oil to fill the filter. And, in the situation described by Web, then run the engine to fill that filter.

    MTV
    Seems over complicated to me. If you want the dipstick to correctly read the quantity of oil in the sump the test is really simple -

    Drain the sump
    Add a known quantity of oil to the sump
    Read the dipstick

  11. #11

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    Drain the sup, service the filter or screen, add to your low comfort zone, like 6 qts, run the engine for a few, let sit, then scribe your dipstick to your known level. If you feel like scribing a high oil mark add oil, give it a few minutes, and scribe accordingly. My Cessna dipstick reads 2 quarts low from actual. I never trust a factory dipstick.

    Coincidentally my Superior sump’s dipstick is perfect on big tires and big gear. I’d expect it to change if I went to stock-ish tires and gear.

    FWIW my fuel dipsticks are made the same way and are specific to the tires installed.
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  12. #12
    wireweinie's Avatar
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    Quote Originally Posted by frequent_flyer View Post
    Is the maximum oil capacity of an engine the sump capacity or does it also include oil trapped in the filter? I had always though it was sump only for Lycoming 0-360 and IO-360.

    If it really is sump only then the dipstick correlation test should be performed before engine run.
    If you mark it for reading oil in the sump and not in the filter or screen, then it will only read correctly once after each oil change.

    Web
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    Is that true? If you really want to know how much oil is in the sump, mark without run-in. If your goal is to know how much oil is in the engine, cooler, prop, etc., mark after running.

    For the smaller Continentals, the important part is how much is in the sump. Too much and they blow it out like quickly. I have no idea why.
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    Quote Originally Posted by wireweinie View Post
    If you mark it for reading oil in the sump and not in the filter or screen, then it will only read correctly once after each oil change.

    Web
    I disagree. The dipstick will always read the quantity of oil in the sump. No, it won't read the total quantity of oil in the engine but what is it that you really want to know?

  15. #15
    wireweinie's Avatar
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    Never found a pilots manual or engine manual that called out the amount of oil in the sump. Manuals only call out total amount of oil in the engine. Since you pull the dipstick before each flight, it would be important to know the amount of oil in the engine at that point in time.

    Web
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    RaisedByWolves's Avatar
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    On all the supercubs ive changed the oil on, add 7 qts after oil and filter and it will read 6 on the dipstick. Stock, 3" 6" gear, 850, 31, and 35's
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  17. #17
    wireweinie's Avatar
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    That because the oil filter was added on.

    Operators can run any amount of oil they wish. The OP was about accuracy of the stick. If you want accuracy then mark the stick according to your aircraft set up during normal operations (Wheels vs floats, etc)

    Web
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    cubdrvr's Avatar
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    I've remarked my fuel gauge to show correct amount at 3 point with 31's.
    Like RBW.....only I add 6 Qts oil.....run mine at 5-6 qts unless long flights.
    31's don't seem to matter on oil. Fine tuning dipstick seems overkill since
    the engine will run from 2-8 qts.
    "Sometimes a Cigar is just a Cigar"
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  19. #19

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    Quote Originally Posted by wireweinie View Post
    Never found a pilots manual or engine manual that called out the amount of oil in the sump. Manuals only call out total amount of oil in the engine. Since you pull the dipstick before each flight, it would be important to know the amount of oil in the engine at that point in time.

    Web


    Copied directly from "Operator’s Manual Lycoming O-360, HO-360,IO-360, AIO-360,HIO-360 & TIO-360 Series"

    Note there is no mention of engine oil capacity only sump capacity.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    I use a “full” line and low limit that I’ve established. With two known levels marked I know what I have and can pretty reliably establish any consumption rates. That some say 2 qts is good enough to operate? It isn’t good enough for me. I prefer accurate information and margins of safety for things like oil and fuel.
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  21. #21
    wireweinie's Avatar
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    Lets say you put a full 8 quarts in the engine and mark the stick as such. Once you start the engine and fill components such as a filter, your stick will now show some level other than the 8 quarts that are actually in the engine.

    But, Hey! If that works for you, then go for it.

    Web
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    mvivion's Avatar
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    Yes, exactly.

    And BTW, in case you decide to run one of these engines at 2 quarts, understand that 2quarts is basically what is required to submerge the pickup in oil….with the engine level. At the Lycoming Piston Engine Service School, the way they explained this was it may be safe to START one of these engines with 2 quarts showing on the stick, but you should ask yourself if it’s safe to FLY it there. Their recommendation was: Don’t.

    MTV
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    Quote Originally Posted by wireweinie View Post
    Lets say you put a full 8 quarts in the engine and mark the stick as such. Once you start the engine and fill components such as a filter, your stick will now show some level other than the 8 quarts that are actually in the engine.

    But, Hey! If that works for you, then go for it.

    Web
    A Lycoming dipstick is intended to indicate the oil level in the sump not the quantity of oil in the engine. I substantiated that in a earlier post but here is more data from the PA28 maintenance manual.

    If anyone has any engine or airframe data that shows the dipstick is intended to show engine oil quantity rather that oil sump level then please share it.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  24. #24

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    Quote Originally Posted by mvivion View Post
    Yes, exactly.
    MTV
    With no quote how are we to know who, or what, you are agreeing with?
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    wireweinie's Avatar
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    These charts state the sump capacity but do not address the stick markings.

    Web
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    Quote Originally Posted by wireweinie View Post
    These charts state the sump capacity but do not address the stick markings.
    Are you seriously suggesting that Lycoming would specify 8 quarts as maximum sump capacity, provide a dipstick with an 8 quart marking, but intend no correlation between the 8 quarts in the sump and the 8 quart marking on the dipstick?
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  27. #27

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    I believe sump capacity is just what it says. How much fluid capacity the sump has. Minimum oil required for operation is expressed separately.
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  28. #28
    wireweinie's Avatar
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    Quote Originally Posted by frequent_flyer View Post
    Are you seriously suggesting that Lycoming would specify 8 quarts as maximum sump capacity, provide a dipstick with an 8 quart marking, but intend no correlation between the 8 quarts in the sump and the 8 quart marking on the dipstick?
    The stick markings are more associated with the installation. Different stick whether the same engine is mounted on a tail dragger or on a nose wheel. Makes no sense to mark a stick at 'full' or '8 quarts' and only make it accurate BEFORE the engine fills a filter.

    Web
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    Quote Originally Posted by wireweinie View Post
    Makes no sense to mark a stick at 'full' or '8 quarts' and only make it accurate BEFORE the engine fills a filter.
    It makes perfect sense if the dipstick is intended to indicate the quantity of oil in the sump. So far no one has produced any documentation that shows that any dipstick is intended to indicate the total quantity of oil in any engine.

    Perhaps someone will produce a Lycoming document that specifies engine oil capacity, or maximum engine oil capacity, or minimum engine oil capacity. I can't find one. All the docs I have looked at specify sump levels and reference the dipstick as a means of measuring that level.

  30. #30
    wireweinie's Avatar
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    Like I said above, if it works for you, have fun with that.

    Web
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    supercrow's Avatar
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    Wow

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    Quote Originally Posted by supercrow View Post
    Wow
    Ha Ha! I’ve typed something similar several times and then deleted it..... Glad I’m not the only one that thinks it may be possible some are overthinking this. The 185 I flew on floats had 2 X’s, low and high. Keep it between the X’s and all is good. Longer flight? A little closer to the top X......
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  33. #33
    wireweinie's Avatar
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    Sorry if I'm slipping into my 'life coach' mode!

    Web
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  34. #34
    mvivion's Avatar
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    Quote Originally Posted by frequent_flyer View Post
    With no quote how are we to know who, or what, you are agreeing with?
    Ummm, seriously….you can’t figure that out? No wonder you’re having so much trouble with the concept of oil in an engine.

    Its not rocket science.

    MTV
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  35. #35

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    Quote Originally Posted by mvivion View Post
    No wonder you’re having so much trouble with the concept of oil in an engine.
    I have no trouble with "the concept of oil in a engine"

    I own and maintain a Lycoming O-360 and a Lycoming IO-360. When I change the oil and filter on each of these engines I add 7 quarts. After engine run for leak check they both show about 6.5 quarts on the dipstick. They are both indicating that there is 6.5 quarts of oil in the sump. There is no indication anywhere that there is 7 quarts of oil in the engine but I know there is because I poured it in and it didn't come out.

    Both engines use factory marked dipsticks and I believe their indications are normal. As you say it isn't rocket science. A correctly calibrated dipstick on a Lycoming O-360 or IO-360 shows the oil quantity in the sump.
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  36. #36
    mvivion's Avatar
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    Quote Originally Posted by frequent_flyer View Post
    I have no trouble with "the concept of oil in a engine"

    I own and maintain a Lycoming O-360 and a Lycoming IO-360. When I change the oil and filter on each of these engines I add 7 quarts. After engine run for leak check they both show about 6.5 quarts on the dipstick. They are both indicating that there is 6.5 quarts of oil in the sump. There is no indication anywhere that there is 7 quarts of oil in the engine but I know there is because I poured it in and it didn't come out.

    Both engines use factory marked dipsticks and I believe their indications are normal. As you say it isn't rocket science. A correctly calibrated dipstick on a Lycoming O-360 or IO-360 shows the oil quantity in the sump.
    congratulations— You got it! And described it well. Good job!

    MTV
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  37. #37

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    Must be a slow airport day.
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  38. #38
    cubdrvr's Avatar
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    Yep.......just a bunch of us dipsticks wondering if we're a half quart low.
    "Sometimes a Cigar is just a Cigar"
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  39. #39
    BC12D-4-85's Avatar
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    Half a quart low = lower oil consumption. The manufacturers figure max burn rate allowed per hour x expected hours of running to leave a minimum in the sump. Too full blows out the reserve from a normal engine.

    Gary
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  40. #40
    skywagon8a's Avatar
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    Since we are discussing "dip sticks", I thought you may be interested in why a certain amount of oil is in the engine.

    PART 3—AIRPLANE AIRWORTHINESS—NORMAL, UTILITY, ACROBATIC, AND RESTRICTED PURPOSE CATEGORIES
    OIL SYSTEM
    § 3.561 Oil system. Each engine shall be provided with an independent oil system capable of supplying the engine with an ample quantity of oil at a temperature not exceeding the maximum which has been established as safe for continuous operation. The oil capacity of the system shall not be less than 1 gallon for every 25 gallons of fuel capacity. However, in no case shall the oil capacity be less than 1 gallon for each 75 maximum continuous horsepower of the engine(s) involved unless lower quantities can be substantiated.
    N1PA
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