oil level reading - simple logic

sure.

oh, wait, many of those engines aren't allowed to cool down, so it must
be ok to never check the oil!!!

/which/ engines? [unsurprisingly] you're being totally non-specific.

so all that bullshit about thermal expansion, calibration, drain-back
valves, etc. is completely irrelevant!!! oh, wait, you don't need to
worry about facts if you're just an asshole.

but according to you, "over-the-road" truck drivers will have to stop
and wait. or not - retard asshole.

 

I am of the opinion that a dip stick is just a rough estimate of the
oil in the pan. I think the idea is to make sure that when the engine
is running there is enough oil left to cover the oil pick-up under all
expected operating conditions. For most cars I am sure the dip stick
is very conservative. I know if I was designing one, the fill mark
would be well above the level at which there was any possibility of
oil starvation. Given all the variables, treating the dip stick like a
calibrated oil level meter is not reasonable. I can think of the
following factors that will affect the accuracy:

Items that effect the initial accuracy versus the specifications
(Manufacturing tolerances that may affect the initial accuray relative
to the specifications but are consistent from one measurement to the
next):
- manufacturing tolerances for the oil pan (no better than +/-0.005"
on each dimension)
- manufacturing tolerances for the actual dip stick (no better than
+/-0.005")
- manufaturing tolerances on the position of the dip stip tube in
the pan/block (probably no better than +/-0.010")
- tolerances on how the engine is positioned in the chassis (i.e.,
angle at which it is installed realtive to the chassis - hopefully the
dip stick is positioned to minimize the effect of this)
- manufacturing tolerances on block/pan interface (probably pretty
tight maybe only +/- 0.002")

Item that effect individual readings (Enviromental factors that effect
the consistency of readings):
- outside temperature
- oil temperature
- grade the vehicle is parked on
- vehicle load (i.e., stuff in the trunk or passenger compartment
that might effect the angle the vehicle is sitting)
- how long the vehicle has been sitting with the engine off before
the oil is checked
- how qucikly the oil "runs" back down the dip stick
- how difficult it is to read the dip stick (some are horrible)
- the reliability / efficiency of the anti-drainback valve in the oil
filter

If you are trying to estimate engine oil consumption you can eliminate
the original manufacturing tolerances by properly filling the
crankcase and scribing a "full" line on the dipstick (or alternately
by carefully adding oil until the level matches the original full
mark). But that only eliminates the original manufacturing tolerances
from the estimation. To get a true view of oil consumption, you would
need to be careful to always park the car in the same location and in
the same orientation. You also need to wait for a long time to make
sure the oil has all drained back into the pan. I also think you need
to try and check the oil with as close to the same ambient
temepratures (after allowing the oil to cool to ambient). If you do
all that, then you could add "make up" oil until the dip stick reading
was back to the full line. But even after doing all this, what have
you proved? You still don't know how much of the liquid in the
crankcase is "oil" and how much is other "stuff" (unburned
hydrocarbons, water, soot, dust, etc.). To minimize the possibility
that contamination is masking the true oil consumption, you would
also need to make sure that the engine was operated long enough and
worked hard enough that the oil got hot enough to eliminate any water
or unburned hydrocarbons.

Personally, I think if you did everything "right" the measuranment
accuracy would still be worse than +/-5% (say a quarter of a quart).

Ed

 

big picture, you're absolutely correct - this is neither rocket science
nor precision brain surgery - the dip stick has two marks on it - "full"
and "add more". between those two, you're fine. but if you're driving
an oil burner, and you're dipping cold and not paying attention, you
could get an expensive surprise.

as for the point about manufacturers being conservative and leaving a
safety margin, that is not something you can rely on. i've seen
vehicles where the oil warning light comes on if the oil is near the
bottom and you corner at speed. clearly, that's /way/ too close for
comfort. otoh, a girlfriend's lexus had the light come on, and that
needed /three/ quarts before it got to the /bottom/ of the stick -
pretty conservative, but clearly not infallible. bottom line - you
can't rely on anything you can't see on the stick - so check the
freakin' oil. hot. on the gas station forecourt. just like it says in
the book.

 

I agree, but was curios about the exact working in my 2007 Ford Fusion
Owners Guide(pictures / engine variations deleted) -

Checking the engine oil

Refer to the scheduled maintenance information for the appropriate
intervals for checking the engine oil.
1. Make sure the vehicle is on level ground.
2. Turn the engine off and wait a few minutes for the oil to drain
into the oil pan.
3. Set the parking brake and ensure the gearshift is securely latched
in P (Park) (automatic transmissions) or 1 (First) (manual
transmissions).
4. Open the hood. Protect yourself from engine heat.
5. Locate and carefully remove the engine oil level indicator
(dipstick).
6. Wipe the indicator clean. Insert the indicator fully, then remove
it again.
.If the oil level is within this range, the oil level is
acceptable. DO NOT ADD OIL.
.If the oil level is below this mark, engine oil must be added to
raise the level within the normal operating range.
. If required, add engine oil to the engine. Refer to Adding
engine oil in this chapter.
.Do not overfill the engine with oil. Oil levels above this mark
may cause engine damage. If the engine is overfilled, some oil must be
removed from the engine by an authorized dealer.
7. Put the indicator back in and ensure it is fully seated.

The line that reads - "Refer to the scheduled maintenance information
for the appropriate intervals for checking the engine oil" caught my
eye, and I followed up by looking at the maintenance guide. The
maintenance guide only specifies checking the oil monthly. They do not
mention doing so at every fill-up. This surprised me.

Ed

 

nothing about frod surprises me. under nasser, that company was
spectacularly ruthless in its cost cutting, and would weasel around
anything it could. [don't get me started on the exploder fiasco.] that
language summarizes as "don't do anything, but if it goes wrong, you're
not covered because you should have done something". nasser legacy
language.

 

<snip for brevity>

All this is fine for making sure the engine has enough oil in it so as not
to seize-up on the roads. The admonition not to add oil during the outlined
procedure is intended to prevent drivers from accidentally overfilling the
crankcase. Depending on the temperature of the oil when checked, a
significant amount of oil can be hung-up in the engine, giving a falsely-
low reading on the stick.

But if your engine uses a significant amount of oil, and you want to
determine exactly how much, then you need a much more exacting and rigorous
method. Like mine.

 

Another brain dead observation, as usual. This is why manufacturers
require checking at gas stations. Your not the first dim wit to buy a
car. there are many drivers like you who wouldn't know what to do if a
manufacturer recommended checking the oil at start up.


Many engines are operated for a shift of work. And it is typically
those types that the manufacturer recommends checking the oil before
start up. The point is there is no reason why checking the oil when cold
isn't an accurate way to determine if the engine needs oil added.

The only reason car manufacturers usually don't recommend checking
oil when it is cold is because they know there are stupid people like
you that will fail to check there oil if for some reason it never has an
opportunity to cool. Those same stupid people won't check the oil at a
gas station either, but that is not the manufacturers problem.

Yup all of that is irrelevant. If you misjudge how much is in your pan
by half a quart - nothing bad is going to happen. These owner's manual
recommendations aren't about how to best keep people from running low
on oil - it is about how to make sure the customer pays for it when they
need a new engine.

Yes retarded assholes do exist - take yourself as a prime example. If
you weren't retarded you would know that truckers are required by law to
stop and wait. They are not allowed to drive longer than a fixed number
of hours. A trucker is usually smart enough to understand that he is
being advised to check oil once every driving shift. The most convenient
time to do that check is before you start the engine. Cummins Engines
for instance, recommends checking the oil before start up as part of a
daily pre-trip prouder. Now if you let the engine idle all night long
then you will just have to check while the oil is warm (unless you are
retarded then you don't know what to do). But most drivers shut down and
will be checking when the oil is cold.
Take another example - school bus drivers. I know a guy who drives
school bus and it is in his employment contract that he check the oil
every morning before starting the engine.

 

From personal experience I can assure you that you are being very
generous. the tolerance for the volume of the pan that holds the oil is
considerably looser than you imagine. The volume of the pan and what the
end user sees on the dipstick is not a major priority for the
manufacturer. Manufacturers are far more concerned about how the oil pan
design is going to perform on the assembly line than how it performs
after the car is sold.

Yes all true, But you can eliminate considerable error by taking only
one dipstick measurement over the entire oil change period. Keep track
of how much make up oil you add and how much it is low before draining
the oil and you have the total consumption.

Taking multiple random incremental readings on the dipstick will only
degrade the measurement accuracy and increase the uncertainty of how
much oil is actually being consumed all together.

-jim

 

no dude, that is a fundamental misconception on your part. the dipstick
is calibrated for the level to be read when hot and just switched off,
not cold and subject to factors i've outline repeatedly above and that
make for massive inconsistency.

example: on some automatic transmissions, they are calibrated to be
dipped with the motor running. if you dip it with the motor off, the
level you will see on the stick is about 3 inches "too high". you can't
possibly argue that departure from the owners manual and approved
dipping method is appropriate in that situation, so why are you trying
to do so here?

only if it's being read correctly in the first place. it needs to be
read hot, as per the calibration and owners manual, not cold and subject
to at least three major variables that lead to inconsistency and
subsequently false readings.

 

wow, i didn't believe you were /that/ stupid. my mistake!

apparently you can't read.

if only...

in your fantasy asshole world!

that's right - reputation and repeat sales matter not a damned bit.

you "know a guy who drives a school bus"?? yeah, "that guy" is you,
loser asshole. and your contract wasn't written by an engineer.
surprised you even read it to be honest, but hey.

 

??? utter bullshit.

part of that "performance after the car is sold" is making sure the
customer doesn't **** up their vehicle under warranty and come whining
for a new motor because they couldn't read the oil level on the
dipstick. asshole.

brilliant! why didn't all those experienced engineers at all those
different independent manufacturers think of that! better yet,
eliminate that costly dipstick thing and oil level monitoring nonsense
altogether! wouldn't need to waste all that paper and ink in all those
millions of owners manuals either!

so, after all that bullying and bullshitting and obfuscation, you
finally and unequivocally spell it out - you don't know what the ****
you're talking about.

 

For most cars, the dipstick is behind the wheel.

 

....of the school bus.

 

Ha Ha Ha you are a joke.
The purpose of checking oil as the manufacturer recommends is to keep
the oil from getting dangerously low.

If however you want to do what the OP is attempting: to accurately
determine the rate of consumption it is not going to produce accurate
results if you base it on a bunch of dipstick readings at the gas pump
every few hundred miles. Even the OP wasn't that stupid.

-jim

 

I think we are in semi-agreement about the inaccuracy of determining
oil usage via repeated dip stick readings. I think it is far to
imprecise to yield repeatable results, but that is just my opinion.

I haven't owned a road vehicle since the 80's that used enough oil
between changes to cause a problem (and even then, it was only a
British vehicle that used a lot of oil). But If I develop a desire to
figure out precise oil consumption for a particualr vehicle I think
I'd do the following:

1. Find a dead level spot and park the car in an easily repeatable
position (heck I might even mark the tire locations). Let the car sit
overnight if possible. Record the vehicle's mileage.
2. Drain the oil completely (let it sit for at least an hour). Remove
the old filter.
3. Reinstall the drain plug
4. Weight the new filter, record the weight of the new filter, then
install the new filter.
5. Weight each bottle of new oil before pouring it into the engine.
Weight the bottle after the oil is poured into the engine. Substract
empty bottle weight from full bottle weight and record the weight of
oil added to the engine. Repeat for each bottle. Record the total
weight of oil added.
6. Start the engine and check for leaks.
7. Allow engine to cool and sit for an extended period of time. When
satisfied the oil has drained back to the oil pan, pull the dip stick
and scribe a line to indicate the "full" level.
8. Drive usual pattern and check the oil level at least weekly.
Monitor the change compared to the scribed line as a precaution. Don't
add any oil.
9. Plan to change the oil whenever the level dropped to the "add"
level or at the normal oil change interval (whichever occurs first).
10. When it was time to change the oil (based on step 9), park back in
the prior spot (step 1). Let the car set in that spot overnight if
possible. Record the vehicle's mileage.
11. Weigh oil catch pan.
12. Drain the oil into the pan. Let it drain for at least an hour.
13. Remove the filter carefully and try not to lose any oil (but have
the drain pan underneath to catch as much as possible should any
spill).
14. Pour as much oil as possible from the filter into the drain pan -
allow to drain for an extended period.
15. Weigh the pan of oil. Subtract the empty pan weight from the full
pan weigh and record the weight of oil.
16. Weigh the filter. Substract the origianal weight (step 4) from the
used filter weight. Assume this is mostly oil and add to the weight of
oil from step 15.
17. Have a sample of oil analysed.
18. Subtract out any moisture, antifreeze, solids, etc. listed in the
oil analysis report from the total weight of used oil (step 16).
17. Subtract the adjusted weight of used oil (step 18) from the weight
of new oil added (step 5). This is roughly equivalent to the oil
consumed over the period. Convert this to quarts (or whatever) and
divide by the mileagae interval (mileage recorded in step 1 minus the
mileage recorded in step 10).

This is about as accurate a method as I could come up with. Will I
ever do it? Probably not. It actually seems insanely complex for a
single person / single measurement, especially considering a precise
measurement of oil consumption for a particualr vehicle is of little
practical value. If I have a car that uses so much oil I need to be
concerned, I am going to get rid of it. I have farm tractors that use
1 or 2 quarts a day when working hard (but they hold 20 quarts). I
just add as necessary. The usage is completely unpredictable. For some
jobs the APPARENT oil consumption is negligible. For other it is
dramatic. Ususaly I check the oil once in the morning and again at
lunch time. Sometimes I have to add a quart both times, sometimes
neither. If the oil usage gets really bad, time for a rebuild. Really
bad in my opinion would be 2 quarts in 4 hours of hard use.

Ed

 

Repeated dipstick readings is like counting all the legs and tails in a
herd of cattle. It could get you the same result as counting heads, but
the chance of introducing error is significantly greater.

It sounds like it should be accurate , but you didn't have the scale
certified and you didn't check the air in the tires

I've driven oil burners in the past and you don't need to be
excessively anal to figure out the rate of consumption fairly close. I
drove a car that burned a quart every 600 miles for about 10 years. I
could predict within 20 miles when it would be at the ADD mark (checked
cold). The first quart after an oil change would go 800 miles but that
was mostly because filling it with 5 quarts brought it up to about 1/4
quart over the full mark.

Fifteen years ago you could get a 2-1/2 gallon container of oil for 6-7
bucks. That was enough to change the oil and keep it filled for about
3800 miles. Driving an oil burner today would be expensive.

-jim

 

er, the joke is on you asshole - you don't understand why though evidently.

no, it's for recreation!!!

so where are your numbers, asshole?

 

Bingo!

The public has been dumbed down to the extent that constant hand-holding
is normal procedure...

<sigh>

JT

 

You can masturbate with the keyboard?

 

Most of which are self-serve, so ...

(I live in NJ, one of the few (only?) states where it's illegal to pump
one's own gas)