Oil level on dipstick...

[guybo]

Originally Posted by humfrz

I make it a practice of checking the oil level after an oil change, before I drive it off the lot. Why?

* to find out if in fact, they did change the oil

* to make sure they put oil in the car

* to determine how much oil they put in the car

I also mark the old filter, so I can make sure it was changed.


humfrz

When I was a kid I didn't do this and one time at a quickie lube place they didn't drain the old oil before putting in the new. Sometimes life lessons are a big expensive PITA

[radroach]

@MuseChaser Mine reads about a half quart over as well even when I'm doing a 5.4 quart oil change (including priming the oil filter. Annoying! I wouldn't blame the service guys.

[mav1178]

Originally Posted by MuseChaser

The car doesn't take 6 quarts.

Actually it does.

I used 6 quarts for every oil change when I had my car, never any issues. The key is to check oil level when the engine is warm, so you can gauge accurate level via dipstick.

As I previously posted, the key measurement is that the oil level is between the marks when warm, not when cold and not when you just finished a change but didn't crank the engine.

-alex

[MuseChaser]

Originally Posted by mav1178

Actually it does.

I used 6 quarts for every oil change when I had my car, never any issues. The key is to check oil level when the engine is warm, so you can gauge accurate level via dipstick.

As I previously posted, the key measurement is that the oil level is between the marks when warm, not when cold and not when you just finished a change but didn't crank the engine.

-alex

Per the shop manual, the recommended amount of oil for a filter and engine oil change is 5.4 liters (5.7 quarts). I've attached a capture of the pertinent portion of the manual.

Yes, you can't get an accurate read immediately after changing the oil unless you start the engine, let the oil circulate for a bit, then shut off the engine and wait a few minutes. If you check the level immediately after adding the oil but prior to starting the engine, it'll read higher than it actually is, not lower. One of my cars doesn't have a dipstick; to check the oil, it insists that the engine have been off for at least 30 minutes to allow as much of the oil as possible to drain down into the oil pan and then the internal sensor will read accurately.

I don't necessarily agree with your assertion that the car needs to be warm to get an accurate reading. The engine has to have been started after an oil change and let run for a bit, and then the oil has to have been given time to settle into the oil pan. When I check my level between oil changes, I ALWAYS check it before I start the car, when it's cold.

I'm certainly willing to listen to rationale for doing it differently. Perhaps things have changed since I started doing oil changes in the '70s.

Best,

Barry

[mav1178]

Originally Posted by MuseChaser

When I check my level between oil changes, I ALWAYS check it before I start the car, when it's cold.

And as I mentioned before, the best time to check oil is when it's warm and after it's been run.

The only thing you need to ensure w/ the dipstick is that the oil is not too low for a chance of oil starvation, and you need to make sure it's not too high for oil cavitation. Only way to make sure the level is sufficient is to check when engine is warm.

You can always check when engine is cold but you also will not know how much oil will stay in the cylinder heads after a drive. Not an issue in a general sense, but it's mentioned in the owner's manual for a reason.

-alex

[gtengr]

Originally Posted by mav1178

You can always check when engine is cold but you also will not know how much oil will stay in the cylinder heads after a drive. Not an issue in a general sense, but it's mentioned in the owner's manual for a reason.

Checking it cold will give a more precise reading. Checking it warm without a waiting period introduces variables into the measurement for no benefit.

[humfrz]

Originally Posted by mav1178

And as I mentioned before, the best time to check oil is when it's warm and after it's been run.

The only thing you need to ensure w/ the dipstick is that the oil is not too low for a chance of oil starvation, and you need to make sure it's not too high for oil cavitation. Only way to make sure the level is sufficient is to check when engine is warm.

You can always check when engine is cold but you also will not know how much oil will stay in the cylinder heads after a drive. Not an issue in a general sense, but it's mentioned in the owner's manual for a reason.

-alex

My take is ....... that the manufacturer "calibrated" the dipstick for the crankcase oil to be measured under a certain condition.

Why are we debating this ......

DANG! cars have had dipsticks since before I was born (and that was a LONG time ago), this isn't something NEW.........

@Tcoat , I haven't received any of those calming pills from you yet .....


humfrz

[MuseChaser]

Originally Posted by humfrz

My take is ....... that the manufacturer "calibrated" the dipstick for the crankcase oil to be measured under a certain condition.

Why are we debating this ......

DANG! cars have had dipsticks since before I was born (and that was a LONG time ago), this isn't something NEW.........

@Tcoat , I haven't received any of those calming pills from you yet .....


humfrz

Lol, humfrz... save some pills for me.. I could use a good calm.

Seriously, I wasn't debating so much as just wanting to learn more about the reasoning behind differing opinions. I've been wrong so many times in my life that I'm more than willing to be corrected when facts show the error of my thinking. On the other hand, there are things that are simply opinion or belief. Many things fall in the grey area between demonstrable facts and beliefs.

In any case, here's a paste directly from the owner's manual...

"Park the vehicle on level ground. After warming up the engine
and turning it off, wait more than five minutes for the oil to
drain back into the bottom of the engine."

I, and others, mentioned the importance of the wait time in previous posts. My reasoning for checking the oil when cold is that I am assured, PRIOR to starting the engine, that there is enough oil in the engine and that no damage will be done starting the engine w/ insufficient oil. If, by some freakish happenstance, a few quarts have leaked out since you last ran the engine and you didn't notice, starting the engine and waiting until it warmed up might be a very bad thing; it'd probably warm up REAL fast.. <grin>. Yeah, I know.. the chances are EXTREMELY remote of any of us OCD anal car nuts not noticing an oil leak that bad, but hey... I check when cold, and KNOW there's enough oil in it.

As far as getting a more accurate reading once the engine is warm (and after waiting at least 5 minutes after shutting it down), I don't dispute that, although I'm not completely sure of the reasoning. Yes, metals and fluids change size or volume w/ changes in temperature, but (and, please, correct me if I'm wrong) I thought that engine oils, brake fluids (and other hydraulic fluids) were engineered so that they WERE stable (i.e., didn't change characteristics) over wide temperature ranges. That, coupled with the fact that our dipsticks really aren't calibrated to give readings down to the milliliter anyway, (and that my dealership seems totally comfortable w/ way overfilling the oil at every oil change), leads me to the conclusion that checking the level when cold satisfies the "wait at least 5 minutes" part, and that whatever error induced by the oil and engine being cold vs. warmed up is small enough not to really matter.

Again, if my reasoning is faulty, PLEASE chime in. I'm here to learn (and crack stupid jokes).

Best to all..

Barry

[MuseChaser]

Originally Posted by mav1178

.....

You can always check when engine is cold but you also will not know how much oil will stay in the cylinder heads after a drive. Not an issue in a general sense, but it's mentioned in the owner's manual for a reason.

-alex

As I quoted in my previous post, the manual also recommends that you wait at least five minutes after you shut off the engine to check the level. I may be misunderstanding your point about "not know(ing) how much oil will stay in the cylinder heads after a drive." The reason for the wait time is to allow the oil to drain back down in to the sump to give an accurate reading. Are you suggesting that you should check the level quickly after shutting down, before the oil settles? If so, why?

Again.. not being argumentative.. just trying to understand your point of view.

Thanks..

Barry

[cjny]

The difference between hot but fully drained oil level vs. dead cold is small but measurable. The oil expands in volume when hot. (If you want to get picky, and obviously some of you do, the oil pan expands when hot too, but not as much.)

[LotsaMiles]

Wow. I've got three cars, a pickup, a tractor,a v-twin rider mower and a 4wd push mower. I've checked a lot of dipsticks, but it dawned on me when I saw this thread that I've not checked a dipstick on a vehicle with a license plate bolted to it since the mid-90's.

I'm a bad boy.

[Tcoat]

Originally Posted by LotsaMiles

Wow. I've got three cars, a pickup, a tractor,a v-twin rider mower and a 4wd push mower. I've checked a lot of dipsticks, but it dawned on me when I saw this thread that I've not checked a dipstick on a vehicle with a license plate bolted to it since the mid-90's.

I'm a bad boy.

I check mine once a month whether I need to or not. I figure any leak large enough to cause an issue I am going to know about in a hurry through smoke and stains and any leak small enough to not be an issue is not an issue.

[MuseChaser]

OK.. I did some more research. One site lists the the volumetric temperature coefficient of oil as about .0007. Plugging that value into various thermal expansion formula websites says that, when heated from 65degF to 200degF, 4.7 US quarts of oil would increase to approx. 4.95 quarts in volume. Basically, that translates into an error of one cup of oil lower when cold than when hot. I'm gonna stick w/ what I've been doing, but it's been an interesting discussion.

Best,

Barry

[Tcoat]

Originally Posted by MuseChaser

OK.. I did some more research. One site lists the the volumetric temperature coefficient of oil as about .0007. Plugging that value into various thermal expansion formula websites says that, when heated from 65degF to 200degF, 4.7 US quarts of oil would increase to approx. 4.95 quarts in volume. Basically, that translates into an error of one cup of oil lower when cold than when hot. I'm gonna stick w/ what I've been doing, but it's been an interesting discussion.

Best,

Barry

Like most car forums people love to focus on fluids. Probably because it is a really easy DIY thing that makes them feel closer to their car. Although I certainly appreciate the need to have the right thing in the right quantity I also am of the mindset of "if there is enough and it works then leave it alone and don't worry about it". There really is no perfect amount of oil but simply a point where there is too little and a point where there is too much. Anything in between is fine and of equal effectiveness.