Dipstick

[19gtaz]

I always have to check it at least twice to get a reading that I can trust.

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[Elp_jc]

Difference from hot to cold is minimal. But good luck trying to get a good read when hot. It's much easier when cold, but still takes a few tries. And yes, the dipstick enters the pan at an angle, so one side will always read higher. I think my dipstick has the hash marks towards the left front tire, which reads a bit low... but I want that, since I only top it off to the top of the hash marks, so it's still below the top dot. That way it's not over the top dot even when hot.

 

[Zooks527]

Why do they want you to run the engine? It should read the same if you run it and wait 15 minutes or if you check it after sitting over night. The more it sits the easier it is to read on mine.

The oil expands significantly as it gets warmer. Unused motor motor oil will gain about 7% in volume for every 100 degree C increase in temperature. Running to full temperature insures that you are always measuring at the same volume conditions. The 10 quart volume in a GT will have a noticeable effect on the dipstick on a day like today, when it's 11 F outside as I type this. Heating my engine to full temperature (~200F) today will result in a volumetric growth of the 10 quarts in the pan of about 3/4 of a quart. By contrast, the 6 quarts in a EcoBoost on an 85F summer day will increase by perhaps 1/4 of a quart. Going to the same temperature every time gets rid of all of the uncertainty.

The 15 minute wait is to insure it has all to drained back into the sump as well as getting some of the splash in the dipstick tube down.

The biggest pain with the dipstick for me is the interference with the strut brace, especially when everything is hot, but, yeah, it's also pain to read.


EDIT: I need to stop posting before I have coffee. The thermal expansion coefficient I used is for SI, not Fahrenheit, so everything in the original post was 80% high. The numbers above are reworked to be correct.

 

[Vlad Soare]

The oil expands significantly as it gets warmer.

In that case, wouldn't it make even more sense to read the oil level when cold? Otherwise you could be low on oil the next time you start the engine, despite getting a perfect reading when it's hot.

 

[Zooks527]

In that case, wouldn't it make even more sense to read the oil level when cold? Otherwise you could be low on oil the next time you start the engine, despite getting a perfect reading when it's hot.

No. Being a quart low when dead cold on a 10 quart engine (or even a 6 quart, for that matter) is well within operating parameters (as the designers know that it will need to be started at multiple temperatures), assuming you're not hammering it while cold into situations where you could get oil starvation at the pickup. Being too high on oil (depending on the engine configuration) can result in oil foaming from the crankshaft, sparkplug fouling, blow-by to the catalytic converter, and other "fun" results.

The other side is that, in general, the bigger the sump, the less sensitive the engine is to single quart swings. My 1.8T Passat, with its 4 quart sump was sensitive to a quart (25%) change. My 7 quart N54 BMW was able to handle a 1 quart overfill from a dealer who wasn't paying attention. The 10 quart Coyote should be even less sensitive, which was likely helpful when the dealer only put 8 quarts in at its first oil change (even after being reminded that it was 10 when I dropped it off ).

You see the same issue these days with sealed automatic transmissions. Filling typically requires you to add a set amount to the cold transmission pan and then run the engine until the fluid runs out of the fill hole at a particular temperature of the fluid. You need to measure the temperature of the fluid (through a sensor, a thermometer in the fluid, an IR scan of the housing, or the like) until it reaches a specific point, at which time you top up (if needed) and then insert the plug into the fill hole.

Given a choice of a quart low or a quart high, take the quart low. But, dead-on is the right place, and dead-on is best measured at full temperature (the point at which the manufacturer sets the dipstick length in design).

 

[Zooks527]

EDIT NOTE: I muffed the numbers in post #19 by using a SI thermal expansion coefficient with English temperatures. The numbers in post #19 have now been corrected, and the non-US portion of the globe needs to get back to using the proper system of measurement.

 

[19gtaz]

Really good info zooks527.
So I've been adding oil on my truck and it's probably been ok.
Now I get to pull the dipstick on the mustang past that brace with a hot engine... fun fun.
I've noticed when I get the truck back from an oil change it's right in the middle when cold.
I wonder if they are doing it right. I've always assumed they just look up on some Ford info chart how much oil it needs and do it that way.

 

[Zooks527]

I've always assumed they just look up on some Ford info chart how much oil it needs and do it that way.

Assuming they're looking at the right chart. The "8 quarts instead of 10" on my car was from a tech who used the 2017 capacity chart instead of 2019, because "Why would it have changed?".

That being said, yeah, your truck might just be at half stick when cold and correctly filled.

 

[Torched10]

I always have to check it at least twice to get a reading that I can trust.

Thanks akitcfircalk the info.ive beenbreadibg it cikdva.

Underline is caused from the activation in the HTML box when replying to a message. Probably just activated it by accident.

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Best way to check the dipstick:
Always check after engine gets to normal Op temps. Shut off vehicle, wait 15 mins for oil to drain back. Pull out once, wipe completely and then reinsert. Pull out 2nd time and try to view it with overhead garage light OR daylight, but looking at the dipstick at an angle.

The oil should be within the designated hashmarks based on your vehicle Powertrain and Owner’s Manual specifications.

Thanks for all the advice.i aimed the cross hatch to left tire and that worked.im,down a quart after 2000 miles,seems high,my 14 Shelby never burned oil.i have noticed on start up the smell of oil burning,it goes away.but it happens every time.is that normal for these engines.wonder if that's where oil is going

 

[19gtaz]

Thanks akitcfircalk the info.ive beenbreadibg it cikdva.
Thanks for all the advice.i aimed the cross hatch to left tire and that worked.im,down a quart after 2000 miles,seems high,my 14 Shelby never burned oil.i have noticed on start up the smell of oil burning,it goes away.but it happens every time.is that normal for these engines.wonder if that's where oil is going

Doesn't seem normal. How many miles are on the engine?

 

[3rdRGR]

Based on a 2019 GT, the owners manual states:

As long as the oil is between A and B, it’s “safe”.

If the oil is ABOVE B, the engine is overfilled and of course if BELOW A, well, you could end up with some major problems....

Sorry, but this is the stupidest design/program in automobile history. It literally takes 20-25 minutes to correctly check your freaking oil and then when you get around to that part (and if you have a very common front strut tower brace) you have to do the freaking hokey pokey to get the freaking dip stick out then the viscosity is so thin that it's running up or down the stick from the moment you start pulling it out. I guess that is why they have a one inch freaking range to make sure you have enough oil. Then to boot many of our cars use oil by nature.... Thaaaaaannnk you...

 

[gadgtfreek]

Just had my oil changed today, 10 qts of 5w-20 Penn Platinum. Got home, let it sit for about 25 mins, then pulled the dipstick, cleaned it, and put it back in. Two concurrent checks, with a wipe in between, showed 3/4 of the way to B. Of course, it is too light to really see, so I just pull the dipstick out and angle the end in some sun. Basically, the highest spot that is consistently "wet" looking is the oil level. As for the cross brace, I just clean the whole thing, and my hands, and use two hands. It isn't difficult.

 

[Torched10]

Doesn't seem normal. How many miles are on the engine?

2000

 

[Tacswa]

No way to tell as it smeared all over when you pull out.

I had a chick tell me that once

 

[19gtaz]

2000

My experience has been that at 2000 mile oil consumption will will get a bit better but 1 quart in 2000 even initially seems excessive. I would like to see half that or even less. That's my experience, maybe others will chime in.

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