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New to car ownership, I was confused by this oil checking procedure in the 2022 Hyundai Tucson owners manual:

Turn the engine off, remove the oil filler cap and pull the dipstick out. Wait for 15 minutes for the oil to return to the oil pan. Wipe the dipstick clean and re-insert fully. Pull the dipstick out again and check the level.

It sounds like I should take out the dipstick and oil filler cap immediately after stopping the car, then leave them off for 15mins before checking. Isn't there a risk of dust etc getting into the oil? Any idea why the manual doesn't just say to wait 15 mins and then check the dipstick?

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    "and the wheels blocked." Nobody chocks the wheels when checking the oil level. Nobody. A typical procedure is check the oil after a drive when the engine is warmed up. Park on level ground and switch off. After "15 minutes" remove the dipstick, wipe it with a clean rag, re-insert, remove and check the level on the dipstick.
    – Weather Vane
    Commented Sep 25, 2022 at 19:33
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    If the requirement is to release any pressure, then unscrewing the filler cap and lifting the dipstick slightly without actually removing them will prevent dust etc getting in. Obviously, the dipstick will need replacing to get a true level. The manual's advice seems to be "you can't sue me if anything goes wrong", but it's bad advice to warm the engine by leaving it parked and running. The best and healthiest way to warm an engine is to drive the vehicle.
    – Weather Vane
    Commented Sep 25, 2022 at 19:43
  • Welcome to Motor Vehicle Maintenance & Repair!
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Sep 25, 2022 at 20:08
  • @WeatherVane The procedure was written by lawyers. I agree with you that it's ridiculous but so is: "Caution: Coffee is HOT!" I expect it to be hot!
    – jwh20
    Commented Sep 26, 2022 at 13:39

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I do not have a definite answer as to why they say to remove it, I see two possibilities:

  1. An abundance of caution: maybe with this or another type of engine there was a case where oil was pressurized and came out of the dipstick when it was removed. I've never heard of such a case but it's possible. The wheels blocked instruction does seem to indicate there's lawyers at work, as you say nobody does that
  2. Accuracy: it's possible removing the oil cap is required to allow the oil to pool properly for a correct reading on the dipstick, by leaving it on you may get under or over-reading

However, your question is asking whether you should follow the instructions, to which the answer is yes. While it's completely possible it's an unnecessary step put in by over-zealous legal specialists, it's more likely there's a very good reason behind it.

As for removing the cap completely, it's easy to miss a cap that's loose as opposed to one that's completely off, and you don't want to drive with a loose oil cap - best case you have a mess to clean up, worst case it's a seized engine.

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  • Just a thought, but you could check the oil as prescribed in the manual, then run the engine, shut it off and wait for 1 minute and check the oil again. See if the readings are the same. If they are, disregard the instructions.
    – X-tech2
    Commented Sep 26, 2022 at 17:06
  • @X-tech2 except the requirement for a warm engine, and waiting at least 1 minute.
    – Weather Vane
    Commented Sep 26, 2022 at 17:27
  • Weather vane, that's what my post says... When the prescribed procedure is followed, the engine is warm. As stated, follow the procedure, then run the engine, shut it off (it's already warm), wait 1 minute, and check it again. If the reading is the same, do the shorter/easiest procedure.
    – X-tech2
    Commented Sep 26, 2022 at 17:48
  • @X-tech2 sorry, you actually wrote "disregard the instructions", which I took to mean: just check the oil level. OP is new to car ownership.
    – Weather Vane
    Commented Sep 26, 2022 at 18:05
  • Weather Vane, I can see where that would be confusing. Trying to move too fast! It's all about getting the correct info out there! Thanks for keeping me straight!!
    – X-tech2
    Commented Sep 26, 2022 at 18:08

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