When To Check Oil (Engine)

Messages
189
Location
NJ, USA
Here is an interesting thing. I was always told that the best way to check engine oil level was in the morning when the car is cold and the oil had time to slide down to crankase. I was told that if you check oil after the car has been driven the dipstick will show less oil then there is. However, on e-how, and some other web-sites they recommend checking the oil after the engine is warm/has been operating. Your two cents?
 

Accord2005NJ

Thread starter
Messages
189
Location
NJ, USA
Luvs2drive, You will not get accurate reading. If engine has been running there will be oil in different parts of the engine and the dipstick will show less oil then there is. Once the oil slides down (which takes time) you get more accurate reading I believe. Otherwise, you may be adding oil to the engine thinking you are short when you are not?
 
Messages
1,294
Location
Western Washington
I check mine after the car sits overnight. I think that owner's manuals may instruct people to check when warm to induce them to check it when they get gas.
 
Messages
2,575
Location
Northeast
you can check it after it has been sitting overnight, or after it has been running. in my opinion it doesnt really matter. if you check it after the car has been running, youre supposed to wait at least 3 minutes. i dont understand how you can ask for peoples .02 on a subject, and then tell them theyre wrong... if you do not get accurate results after running the engine, how do you check the level after an oil change? do you add oil, and then just check the level? to me, that would give the most inaccurate readings. i add oil, run the engine for 1 minute, let it sit 3+ minutes, and check it again. the level after 3 minutes always matched the level when the engine was cold after sitting a long time
 
Messages
2,575
Location
Northeast
i'm not being sensitive. luvs2drive said this "Best checked when warm. Let the car sit for 5-10min after shutdown and check." you said "You will not get accurate reading. If engine has been running there will be oil in different parts of the engine and the dipstick will show less oil then there is. Once the oil slides down (which takes time) you get more accurate reading I believe. Otherwise, you may be adding oil to the engine thinking you are short when you are not?" to me, that sounds like you are telling him that the way he checks his oil is wrong. if that is not what you are saying to him, my mistake. it is the internet, and thus it is sometimes hard to tell what type of tone others are using.
 

JHZR2

Staff member
Messages
46,166
Location
New Jersey
maybe its a NJ myth? I was always told that the pump attendants (were in NJ mind you) always ask to check the oil because it will be low after operating, so they can sell you a pricey quart of oil... Me, I check it in the morninf sometimes as its easy, and when hot sometimes when thinking about it... never much of a difference. If its real low, its real low no matter what, and if its right, its right... not much of an issue beyond that. JMH
 
Messages
2,055
Location
Toronto-ish, Canada
Check your manual, it will say what they intended. There are two factors: where is the oil and what temperature is it. A large percentage of people are saying "check in the morning" because all the oil is in the crankcase. It's also at ambient temperatures, which could be quite cold, and have condensation in it depending on the kind of night you just had. All of my manuals so far have indicated that oil level should be checked when the engine is hot after resting something like 5-10 minutes. This gets most of the oil to the crankcase, but it is still warm so there is no condensation and the oil has expanded to the "proper" volume to read a level. Remember that cold oil will be slightly lower volume. A 4L crankcase might not show much difference, but a 12L dry sump oil system would. Bottom line, read your manual, they put the marks on the dipstick. Craig.
 
Yes indeed. After an engine is hot and left to sit for 5min or so, all the oil that is going to be in the crankcase is going to be there. I've used both methods to check oil. Like some experiences here, I've rarely seen much difference. My strict belief though is that you'd want a reading with some of the oil in the galleries anyway. Under certain conditions a good chuck of the oil is up in the block and leaving very little oil in the crankcase for splash lubrication. In some extreme cases, you can have a near empty pan leaving the oil pump sucking air. Case in point, my old 1998 Ford Contour. Roush did some testing (after Ford was reporting spun crank bearings) and found that under some conditions (hard acceleration/hard cornering) the oil pump was strong enough to suck the pan dry and have it all up in the block. A bit of a design flaw, sure, but they recommeded a fix of adding 1qt more oil to the crank case. This would help prevent a spun bearing. So with this knowledge I prefer to check my oil just after shutdown. If I add a little oil beyond normal, I'm not concerned. I've always had a little more oil than my max line and never had any issues. Ultimatly though, as long as you check it, and you do it the same way each time, I think you'll be fine. After all, it's not rocket science! [Big Grin]
 
Messages
11,385
Location
Florida, Cape Coral
Overnight cold is most consistent but, I also check at every gas stop usually. When hot I check after 5-10 minutes and realize that oil expands and may show a 1/4" higher than when cold.
 
Messages
1,910
Location
Vista, CA
How 'bout a science project. Check the oil at 2-3 minutes after shutdown. Then check it in the morning and see what the difference is. Now you have a reference for future checks. You won't have to take someone's word for choosing the best method. Infact if you don't have a life, you could check at 1 minute, then two minutes, then three minutes, then... You could make a spreadsheet and report your results. Be sure you include weather, brand and viscosity of oil, car make and model and mileage on both the oil and the car. [Patriot] I'll start, my 84 Honda Civic with 380k plus miles in Southern California has a 1/16" difference between one minute and overnight, with 5w-30 oil.
 
Messages
2,055
Location
Toronto-ish, Canada
quote:
Originally posted by Eddie: Overnight cold is most consistent but,
Every night is the same temperature where you are? I would think that, in the absence of a real thermostat controlled oil cooler, hot engine operating at the thermostat-controlled operating temperature would be the most consistent.
 
Messages
172
Location
Louisiana
I check mine every 1000 miles or so. About 20 - 30 minutes after I turn off the motor. Oil is still warm and it's had time for most of the oil to settle back in the pan.
 
Messages
166
Location
Alamo, TN
I just changed the oil in my son's Highlander and when I check the oil, I can't really tell what the actual level is versus the oil from the dip stick tube. The oil is still so clear after a couple hundred miles, that it is hard to see. I am checking it warm after about 10 min. What prompted this is, I forgot to close the Fumoto valve thant I had installed the previous change and some leaked out. Since I wasn't sure how much I lost I tried to guess how much to add. After everyone has a good laugh, some serious answers about problems of too much or too little. Probably within 1/2 qt. alamogunr
 
Messages
1,899
Location
Columbia, SC
I'll check mine at the gas station after I have pumped the gas and cleaned the windows. It has had plenty of time to drain to the pan. Have you guys ever watched a mechanic do it? They change the oil, crank the car, turn it off and let it sit for a few minutes before verifying the level. Anyway, between the two (basically anyway) options, I doubt 1/8 at the full mark is going to matter any. My concern would be if it was at the low mark and even then, why did you let it get that low to begin with!
 
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