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Checking the engine oil

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Capra, May 7, 2019.

  1. Capra

    Capra Senior Member

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    Does this have to be done at full operating temps? Why did MB opt for this method?
     
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  2. Naraic

    Naraic Moderator

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    Nope.
     
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  3. Wighty

    Wighty Senior Member

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    My users manual says check the level hot after being parked for a few mins . I like the dipstick level to be at 3/4 above minimum (but that's me)
     
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  4. OP
    Capra

    Capra Senior Member

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    I should have checked the manual, thanks Wighty.
     
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  5. Jim2

    Jim2 Senior Member

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    Strange Wighty....I was unaware that the engine oil needed to be hot when it's being checked...:shock:....thats complete new's to me ( but then again, you learn something new every day !!! LOL,) But like you though,I'm happy enough with the level sitting 3/4 above the min, and cold at that...must check it hot, and see how it looks then. Is your's the OM651 engine too?
     
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  6. EmilysDad

    EmilysDad Senior Member

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    I always checked oil levels cold too, then I bought a Smart & a Merc .... lol
     
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  7. Wighty

    Wighty Senior Member

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    I want to begin with :eek::eek::eek: :)D) , and finish with I bet it's over max when hot :(
     
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  8. d215yq

    d215yq Senior Member

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    Whats the point of them calibrating it hot? As i understand, you have to wait for it all to drain back after driving so that leaves a small window and variances...why wouldnt they make the marks like everything else and assume its checked cold. I check all levels when convenient to me i.e when i have timeand its cold and parked level, not 20 mins after a long journey when thats the last thing i want to do. Surely everyone else does the same?
     
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  9. OP
    Capra

    Capra Senior Member

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    That is why I asked the question? Sounds odd, but maybe other manufacturer do the same? Or maybe something to do with such a large quantity of oil, but that would indicate that a fluid takes more room when hot?
     
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  10. Tony Dyson

    Tony Dyson Senior Member

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    It doesn't matter whether hot or cold, stop engine, leave for 5 Mins if hot for oil to drop to sump, 20 Mins if cold, correct level is anywhere between Min and Max top up if near Min.
     
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  11. EmilysDad

    EmilysDad Senior Member

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    Temp does make quite a difference to the level on my Smart ..... there's not much oil in it to start with. ;)
     
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  12. Jim2

    Jim2 Senior Member

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    Yes, I agree. Habits of a life time are hard to break.....I will continue to do my checking 1st thing in the morning, when the engine is cold, and once it show's 3/4 above the MIN mark, I'm happy. When I'm changing it, of course, it will be hot, and then I monitor the amount drained....inc. filter, it's 6.5 Litres, so I will allow a little be less to fill...to allow for the fraction that still remains in the engine. So far, it has worked out very well for me, But I have read here on the forum, that some of the newer engines don't even have dipstick/.... all measured electronically !!! ????
     
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  13. ajlsl600

    ajlsl600 Senior Member

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    i check cold. but allow it to be a few mm low to take expansion into account. trans is a different matter tho .
     
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  14. moj91

    moj91 Senior Member

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    I check hot +10 mins on my OM651... which currently reads 1/4 above max... erm... thats for another thread.
     
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  15. ajlsl600

    ajlsl600 Senior Member

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    thats about where mine was this am. cold .but 4mm down when i finished the job yest. i was brought up with the whole idea of knowing the level is correct BEFORE turning the key , not 20 min later and potentially somewhat to late ! another thing i like to watch for is any unknown increase in level , like diesel getting in the oil for example .
     
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  16. Jim2

    Jim2 Senior Member

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    As a test, I will try it both way's. 1st thing in the morning, cold. And hot after a long drive +5 mins. I will see then how much a difference is made by the Temperature.
     
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  17. Submariner1

    Submariner1 Senior Member

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    I was told by a top techy at Mobil, that you must check it at full operating temp if you use Mobil 1 0W40, as it really expands. So to ensure you don't overfill check when red hot.
    Apparently if its too full it can beat it into a frothy constituency. Which has a bigger volume , sort of a vicious circle getting worse and worse. And the frothy oil doesn't protect bearings properly.

    Hmm I thought that all seemed a bit exaggerated. So I checked it cold, and then red hot. Wow a big difference on a 5.5L!

    Never run an engine overfull ... so no idea if the frothing aspect is true. And ain't going to try. :)

    So I guess thats why MB stipulated check when hot.
     
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  18. Jim2

    Jim2 Senior Member

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    Yes, it's well understood that liquid's expand when hot, so from that viewpoint, it makes sense to check when hot. MB would be well aware of this too, inc. when they give the oil qty for the OM 651 engine as 6.5 Ltrs. ( 2010, E class W212 ) So when I change the oil in mine, I drain it via sump stud ( no vacuuming ) and change the filter as well. I fill only 6 ltrs back into the engine and run it for awhile and then check it. Once It's between Min-Max, I leave it be until after I have driven it for awhile before checking it again. It may need a few Ml to bring the level up another little bit, but after that I only check it in the morning's after it has been parked all night. The question is, if MB recommends 6.5 ltrs for that particular engine, and you do not over fill it, then it should be correct, regardless of the temp? Certainly, if I found it to be over the limit when I check it in the mornings, I would suck the excess out.
     
  19. Jim2

    Jim2 Senior Member

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    So this morning I checked the oil level before starting the engine ( See "COLD" Pic). Then again after a 50 mile drive ( See "HOT" Pic ) I let the engine cool down for 5 mins before dipping it.
    As can be seen from the pics, the level hot or cold, is 100%. So I will continue my usual practice of cold engine dipping. But will pay more attention than ever at oil change time's.....monitor exactly the amount drained, and replace the exact same amount, which should be somewhere 6-6.5 ltres max.
     

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  20. CrustyClam

    CrustyClam Active Senior Members

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    I randomly check hot and cold, hot gives a higher reading on dipstick.
     
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