Checking engine oil: Which is the correct reading?

Hello!

I have a 2005 Toyota Camry. When I checked the oil on the dipstick after the car has been sitting over night, the oil was at the “full” mark.

Then, I drove around for 20 minutes, turned the car off, and let the car sit for ten minutes. After that, I checked the oil again and the dipstick seems to be very wet with oil by the “low” mark, and only slightly damp around the full mark (nearly dry).

Which one do you think is the correct reading?
Do you think my oil is low?

When you check the oil, do you remove the stick, clean it, put it in, then check it? If so, then I’d trust the morning reading.

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The reading shows lower after you’ve run the engine because a lot of the oil is still in the engine.

The dipstick measures the oil in the bottom of the oil pan, which is where the oil stays when the engine is cold.

The “cold” reading is the correct one.

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I don’t. When I check it first thing in the morning, I just pull the stick out and check it. Always seemed to me like that is the best way, as all the oil is settled. If you pull it out, clean it, stick it back in, and check it again then you’re potentially smearing oil on the dipstick tube the first time you pull the stick.

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That might work for some engines and not for others .

I like to have one routine I use regardless of the time of day, engine hot/cold, etc. Never had an issue with using it in the morning.

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Maybe, but I don’t see how. A dipstick is a stick, an oil pan is an oil pan. Never understood wiping the oil off the stick and sticking it back in if the engine hasn’t been started. The only thing to wipe off is the oil.…which corresponds to the level of the oil at rest.

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I don’t have any issue with that. I do think you’ll get the most accurate reading just pulling the stick if the engine hasn’t been run and just checking. Generally not an issue either way.

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In the AM, take out the stick and see the level it shows. Then wipe it off, put it back in, pull it out and check the level again. Is there a difference? If so, the second reading is correct.

Why is the second reading correct?

My owners manual, different manufacturer, states to drive the car until all fluids are fully warmed up, then wait 15 minutes after turning off the engine to check the oil level. I get the same reading when checking it cold.

I’ll admit, I’ve never read the procedure in the manual. But I don’t see the sense in starting the engine, letting the oil circulate through it, shutting it off, then waiting 15 minutes for the oil to return to the oil pan (where it was before you started the engine :thinking:) to check the oil. This does make sense directly after an oil change, though, to get the filter full of oil before you check the level.

The reading taken a few minutes after stopping the engine is correct. Oil was commonly checked at gas stations, and the car had to be driven to the gas station.

It compensates for two things:

Any oil that had splashed up higher on the dipstick and crept down overnight.

Any oil that, through surface tension, crept up from the pool of oil in the engine.

And you are wrong again . There are a few engines that need more than a few minutes for the oil to drain back to the oil pan for a correct reading . One size does not fit all .

I can get a correct reading just pulling the stick on our Volvo cold but the Ford Fiesta requires the wipe then check method.

Fords with certain ecoboost motors require several minutes, and often get over filled by those who check a hot motor too quickly.

I have no formal schedule or discipline for checking oil. I check it when it’s convenient and when I think about it. If the cars haven’t been run, I just pull the dipstick. If they have been run I wipe then check. There can be a little variation in the level that I expect and don’t worry about. If it is down half a quart, I’m more careful in checking and add some, then make a mental note that it is time to change oil.

Now on my small engines I wipe stick first to get any kind of accurate reading.

It really is the trend though rather than and precise reading at any given time.

You didn’t expect him to be right did you?

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It took hours for the oil to drain back into the oil pan with my 2013 Chevrolet Equinox with 2.4 4 cyl engine. I got into the habit of letting it sit overnight before checking the oil level. It had the oil consumption issue and the engine was rebuilt at 42k miles. Even after the rebuild I tracked the oil level precisely to monitor for signs of oil consumption.

Ed B.

Surface tension would have to overcome gravity for the oil to “creep up”, right?

Also, the second reading doesn’t compensate for the oil you just drug up into the dipstick tube when you pulled the stick out the first time.

I don’t know, I think some are overthinking it. It’s literally a stick with marks on it dipped into a liquid to estimate the volume of that liquid. Still seems most accurate to me to check it when the liquid is undisturbed.

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