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I notice when checking the dipstick sometimes it is black or brown at bottom and gets lighter at top.

Why is this?

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  • Had you just topped the oil off? – Pᴀᴜʟsᴛᴇʀ2 Oct 17 '18 at 22:15
  • Daft question but you have wiped the dipstick clean before taking a dip reading? – Steve Matthews Oct 18 '18 at 12:45
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    @SteveMatthews yes, of course. – James Wilson Oct 18 '18 at 15:57
  • did you run the engine yet? – agent provocateur Oct 19 '18 at 19:21
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There can be a number of factors causing this:

  • If you've just topped the oil up but not driven the car yet then the fresh oil is sat at the top

  • The darkening/blackening you see is caused by dirt (for want of a better word) in the oil, if these particulates are heavier than the surrounding oil then they will tend towards the bottom of the oil as it settles.

  • Assuming your dipstick is vertical then as you pull it out gravity pulls more of the oil towards the bottom of the stick, making it thicker and therefore darker

  • Since the top of the oil on the dipstick indicates the top level of the oil in the system it's entirely possible that natural sloshing has splashed some oil there rather than it being fully immersed. So there's less oil there making it appear lighter.

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It could be dirt accumulation on the dipstick from before the oil change. It reaches to where the old oil level was. You can try to clean the dipstick with some solvent. Petrol could work.

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