Checking Oil

Messages
173
Location
Indiana
I was at a gas station today and I saw a guy who was probably in his mid-60's pull up into the gas station, he hops out of his car and pops the hood. He checks his oil, and then he adds 1 quart of Amsoil Motor Oil, I only mention the motor oil because I knew members would be asking what brand of motor oil he was pouring into his engine. Regardless of whatever motor oil he was pouring into his engine, I was taught that you should check your oil when the engine is cold, because if you check the oil when the engine is hot you will get an incorrect reading since some of the oil can still be in the top of the engine. I felt like saying something, but I kept quiet.
 
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Messages
1,107
Location
CA
So is this an issue for mechanics? I would like to bring my car to the mechanic after 20 to 30 minutes of driving so that he can drain the old oil out hot. But then when he fills up, presumably the engine is still hot, warms up the new oil, and makes it hard to check the level?
 
Messages
36,537
Location
ME
Take out your drain plug. Pour a quart of oil in. It'll come right out. Oil doesn't stick to the top of the engine. If you look at a typical head gasket the oil gets a 1/2 inch hole straight shot back down to the pan. This is not an issue for mechanics; they add the spec'd amount and check the stick; if it's within a couple millimeters they call it good.
 
Messages
89
Location
Canada
According to the VW manual you should drive to car to bring it up to temperature and then wait 10 to 15 minutes to allow the oil to run down into the pan. What I don't understand is why not just do it on a cold engine. Why run the car first?
 
Messages
22,707
Location
Apple Valley, California
You don't want to check the oil immediatly after turning it off. A few minutes should be enough time for any oil in the top to run down into the pan. I think that by the time the gas pump is done pumping gas the oil could be safely checked.
 
Messages
1,392
Location
Charlotte, NC
I've never had any specific procedures outside of wiping the dipstick tip off with a paper towel the first time I pull it out, reinsert and pull it out and take that as my reading. I do it the same cold or hot and come away with the same reading.
 
Originally Posted By: Bayman
I was at a gas station today and I saw a guy who was probably in his mid-60's pull up into the gas station, he hops out of his car and pops the hood. He checks his oil, and then he adds 1 quart of Amsoil Motor Oil, I only mention the motor oil because I knew members would be asking what brand of motor oil he was pouring into his engine. Regardless of whatever motor oil he was pouring into his engine, I was taught that you should check your oil when the engine is cold, because if you check the oil when the engine is hot you will get an incorrect reading since some of the oil can still be in the top of the engine. I felt like saying something, but I kept quiet.
If it was below the add line I don't think "waiting for a more accurate read" would make much difference..... shrug
 

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Messages
46,238
Location
Ontario, Canada
Originally Posted By: fredf
According to the VW manual you should drive to car to bring it up to temperature and then wait 10 to 15 minutes to allow the oil to run down into the pan. What I don't understand is why not just do it on a cold engine. Why run the car first?
This is what BMW recommends as well. 15 minutes.
 
Messages
28,123
Location
Regina, Saskatchewan, Canada
Originally Posted By: Papa Bear
If it was below the add line I don't think "waiting for a more accurate read" would make much difference..... shrug
Bingo. It's fine to let it sit, but hot versus cold isn't too crucial for checking it. Running a cab fleet for years, I don't think I ever checked the oil on a cold engine. It would happen after a fillup or after a cleanup.
 
Messages
3,181
Location
Ohio
Originally Posted By: fredf
According to the VW manual you should drive to car to bring it up to temperature and then wait 10 to 15 minutes to allow the oil to run down into the pan. What I don't understand is why not just do it on a cold engine. Why run the car first?
Possibly because the last time the engine ran it wasn't hot when shut off. The owners manual wants to make sure it was hot. For example my Regal: When it gets close to closing time in the dead of winter, I pull my car into the shop to let the snow melt off of it. If the engine only runs 1 minute from the parking lot to the bay and I check the oil, it always reads low (.5 to .75 qts.) Let it sit for an hour, it reads the same (still low.) Drive it home (20 mins) and park it (overnight.) Check in the morning and the oil is exactly full.
 
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Messages
253
Location
NJ
I think it also depends on the motor. My Cyclone always reads half a quart low after running, but gets noticeably higher when stone cold. My Prizm never varies whatsoever.
 
Messages
5,968
Location
Houston, Texas
If you do that to my engine you'll be adding about 3qts to bring it up to the full mark. It all depends on the engine. I wouldn't advise adding oil the second you shut the engine off. I'd give it atleast 10min for most vehicles. Big diesels i'd give 30 minutes for it to drain back to the pan.
 
Messages
3,258
Location
Indiana
Originally Posted By: Chris142
You don't want to check the oil immediatly after turning it off. A few minutes should be enough time for any oil in the top to run down into the pan. I think that by the time the gas pump is done pumping gas the oil could be safely checked.
Bingo !! this is my "on the go method" of checking oil. When i do a OCI at home i do it after the auto has sat all night, then pull the plug and forget it for a bit.. when i no longer see it dripping, thats good enuff for me. I have friends that argue that it takes to long doing a oil change with the oil cold, and that warm oil emptys much faster (obviously).. i dont argue with them, i think either way is OK, just as long as the oil has stopped dripping so that the most comes out..
 
Messages
882
Location
USA
actually......most of the oil goes back to the pan within minutes. after a few minutes, it begins to drip into the pan and doesnt effect the readings.
 
Messages
778
Location
A Warm place to live in
I like to check my oil level after a few hours of getting home, seems safest for accuracy. But we really don't know if the guy's reading was below the "add oil level" and therefore he felt safe enough to immediately add a full quart.
 
Messages
3,203
Location
Southeastern, PA
In the scheme of things, I'm more concerned that people don't check their oil. I'd like to dress-up as the Casterol Scottish guy and approach those negligent drivers. "Do you no check yer oil???" "Get your lazy arse out of that driver's seat and check yer oil!" Then I'd approach the front of the car and start wailing on the hood with a dip stick. "Check yer oil!" [whap], Check Yer Oil!" [whap],"CHECK YER OIL!!!" [whap]. That should get some attention. grin
 
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