Oil Change - Hot or Cold and Oil Level Check - Hot or Cold?

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Sep 25, 2017
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Hello my fellow oil enthusiast! Hope you all are having a wonderful day.

I have a couple questions that I was thinking about and they have my curiosity.

Question #1. Is it best to change your vehicles oil when it’s cold or when the oil is hot from the engine getting up to operating temperature?

Question #2. Is it true that most engines, even when you drain the oil, will still hold up to half a quart of oil internally? Is this is the case, wouldn’t it be best to put half a quart less in at the oil change then what the vehicles manual says so that when it’s checked it will be at the full mark and not overfilled?

Question #3. Should you check your engines oil level when the engine is cold or up to operating temperature? Reason I ask this one is because when oil gets hot it expands and can cause the reading in the dipstick to show half a quart to much oil.

Can’t wait to read everyone’s answers. Enjoy the rest of your day my fellow oil enthusiast! Cheers.
 
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1. After about 5 mins of car on. Unless you want to burn yourself.

2. Yes. car manufactures have that in mind when they dictate how much oil to use in an oil and filter change.

3. Check when car is cold.
 
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#1 - neither...warm. As for me, I'll change it first thing in the morning and just give it extra time to drain out...beats getting burned.

#2- No, the manufacturer probably has taken that into account. Plus, the capacity stated in the owner's manual...I find to be low...I always have to add about 1/2 quart over the stated capacity to get to the top mark on the dip stick...even sitting for a long while.

#3- what??? If it did, I don't believe its a significant amount of expansion. In fact, I find that the oil level reads a little lower after driving because some of the oil hasn't settled into the pan. Hence, many will state that you need to let the vehicle sit for several minutes before reading the oil level.

Don't get so hung up on it...it is a relative reading not an absolute. How do you know your vehicle is sitting 'perfectly level' when you check it?
 
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This has been asked numerous times, here are a few previous threads.

 
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#3 It depends. Sometimes an owner's manual will specify whether to check the oil cold or hot. My '99 Northstar manual had a 7.5 quart capacity, kind of unusual for 1999 I might add. Anyway, it said to check the oil level when hot.

To question #2. The oil that stays in the engine, stays in the engine, so no.

#1, Personal choice. I prefer warm.
 

BlueOval83

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This has been asked numerous times, here are a few previous threads.

Thank you. I’ve been a member for a while, I just never have posted before and I’ve read a bunch of threads on other forums about it and could never get a clear answer so I thought I’d ask here since you guys are all oil enthusiast. Figured I’d get the best response here.
 
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Prius:
1626286108731.jpg

My Ram says the same.
 

BlueOval83

Thread starter
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Sep 25, 2017
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#3 It depends. Sometimes an owner's manual will specify whether to check the oil cold or hot. My '99 Northstar manual had a 7.5 quart capacity, kind of unusual for 1999 I might add. Anyway, it said to check the oil level when hot.

To question #2. The oil that stays in the engine, stays in the engine, so no.

#1, Personal choice. I prefer hot.
My owners manual says to get it up to operating temperature, turn it off and wait 15 minutes but every time I do that it still never reads right. It’s still showing to high when I do it that way even though it only has 4.5 quarts of oil in it which is what the manual calls for. Funny thing is if you check it cold it’s right on the money on the full mark. I guess even owners manual can’t get it right either.
 
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Question #1. Is it best to change your vehicles oil when it’s cold or when the oil is hot from the engine getting up to operating temperature?

Question #2. Is it true that most engines, even when you drain the oil, will still hold up to half a quart of oil internally? Is this is the case, wouldn’t it be best to put half a quart less in at the oil change then what the vehicles manual says so that when it’s checked it will be at the full mark and not overfilled?

Question #3. Should you check your engines oil level when the engine is cold or up to operating temperature? Reason I ask this one is because when oil gets hot it expands and can cause the reading in the dipstick to show half a quart to much oil.

Can’t wait to read everyone’s answers. Enjoy the rest of your day my fellow oil enthusiast! Cheers.
1. It is best to change oil when the engine is at operating temperature. Multigrade oil (such as 5w-30) becomes less viscous (thinner) as the temperature increases, allowing for higher flow rate. This isn't to say that changing cold oil won't work, but hot oil will drain faster than cold oil.

2. Some oil will cling to metal parts, remain trapped in nooks and crannies, and be trapped in oil cooler lines. How much oil depends on the vehicle in question. My personal process is to short the fill by 1/2 quart and add a final amount as needed.

3. Checking when cold is ideal. This will allow the highest amount of oil to return to the oil pan to give a "true" level. Checking when hot should be treated as a "reference" of whether or not a somewhat ideal amount of oil is present, as yes, liquids tend to expand when how, and also referencing back to 2., not all oil will return immediately back to the pan when you stop a running engine.
 
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Hello my fellow oil enthusiast! Hope you all are having a wonderful day.

I have a couple questions that I was thinking about and they have my curiosity.

Question #1. Is it best to change your vehicles oil when it’s cold or when the oil is hot from the engine getting up to operating temperature?
Cold or hot no real advantage or disadvantage, either way let the oil drip out as long as you have the patients for?
Question #2. Is it true that most engines, even when you drain the oil, will still hold up to half a quart of oil internally? Is this is the case, wouldn’t it be best to put half a quart less in at the oil change then what the vehicles manual says so that when it’s checked it will be at the full mark and not overfilled? Hmm well sorta goes with the answer #1

Question #3. Should you check your engines oil level when the engine is cold or up to operating temperature? Reason I ask this one is because when oil gets hot it expands and can cause the reading in the dipstick to show half a quart to much oil. Well if you want to get technical oil will slightly expand but I cant say so much that it make that much an impact on the engine oil sump of most daily driver production vehicles.

Can’t wait to read everyone’s answers. Enjoy the rest of your day my fellow oil enthusiast! Cheers.
I think you will be just fine
 
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Funny thing is if you check it cold it’s right on the money on the full mark. I guess even owners manual can’t get it right either.
I've never been accused of this personally, but did you ever wonder if your dipstick is too long?
 
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