Thermal expansion

[OldCowboy]

Originally Posted By: 45ACP

Im not going by advice in car manuals... im going by advice of my family that tinkers with their cars for years and likes to take muscle cars to the tracks on weekends.....

We also dont follow car manual advice about oil recommendation, as to viscosities.

Wow! It's truly amazing that you and your family know so much more about cars than the engineers and manufacturers that build, warranty, and service them. Perhaps you should write a book to share your extensive knowledge with the rest of the world.

 

[fdcg27]

Listen to advice born of experience.
Engineers don't write owners manuals, marketing and legal folks do.
The whole point of this site is to share real experience.
If someone with real long-term experience posts, listen to them.
I'm not saying that we should all accept everything anyone posts without some critical thinking.
I am saying that we should not dismiss a post with the old "engineers and manufacturers" reply.
If all we needed were what is written in owners manuals, there would be no BITOG, nor would there be any need for it.

 

[Eddie]

My vehicles, including my 2007 Mazda CX7 states that the oil should be checked 5 or more minutes AFTER the engine is shut dowm. I find that owners manuals are pretty well written and tend to be simple for those who think they know-it-all.)

 

[45ACP]

Originally Posted By: OldCowboy
Originally Posted By: 45ACP

Im not going by advice in car manuals... im going by advice of my family that tinkers with their cars for years and likes to take muscle cars to the tracks on weekends.....

We also dont follow car manual advice about oil recommendation, as to viscosities.

Wow! It's truly amazing that you and your family know so much more about cars than the engineers and manufacturers that build, warranty, and service them. Perhaps you should write a book to share your extensive knowledge with the rest of the world.


We check it cold, and its never a problem. I dont think i ever said that engineers dont know what they are talking about. Only letting you know the tried-and0-true method of "Check it ice cold, first thing in the morning or when you come out to the car so all the oil is actually in the crankcase. Then make sure its at the max."

A lot of other people do too. Im not sure i see the problem here.

A lot of other people also run, oh, say, different than recommended viscosities than that manual you speak of.

I dont trust a hot reading. Its not dripped down from the head yet. To me, its that simple.

Also, our owners manuals have a tendency to stay in the glve box for life. Call it a "sealed for life owners manual." We tinker with cars, we know what it says. Does not mean we actually do it.

And those track machines? Boy..

- lol. Ill bet those come with owners manuals too. There isnt an "install roots-type supercharger properly" section.

We really dont have to get into what different owners manuals say in different countries, do we?.

 

[ammolab]

Marketing folks write BROCHURES, not operating manuals.

My BMW Motorcycle manual explicitly warns about checking oil level on a COLD engine due to the changing oil level due to the oil not being up to "operating temp".

Remember the dipstick was invented and calibrated for us when Gas Jockeys checked the oil after a shut down for fueling. That is just what I do today and is pretty much what every manual I have ever read requests. Hot engine, shut down...wait 3 to 5 minutes for oil to drain into the crankcase and then give it a check.

You will not destroy your motor by making up your own routine. That is the fate of those who just NEVER check the darn oil. Speak to a repair shop...there are PLENTY of those folks around.

 

[Loobed]

Originally Posted By: 45ACP
Originally Posted By: Loobed


My old 1984 911 would read a quart difference between ht and cold. My 911 sump was 12 quarts.





What oil weight did you use in that car.


I used 20w-50. Sometimes I would use 10w-40. I used whatever I got on sale. Usually $1 a quart.

 

[Mitch Alsup]

Originally Posted By: 45ACP
IIRC, it is not a good idea to check oil level when car is at operating temperature because it is not an accurate reading!


This depends on the engine and sump architecture. Dry sump engines have the oij level checked within a few seconds of stopping the engine after the oil is a full operating temperature. The dip-stick of a dry sump engine is in the dry sump. If you check it after it has cooled, all the oil will have flowed backwards through the pumps and be residing in the crankcase.

Wet sump engines should be checked later after the oil has a chance to get back to the sump.

 

[Garak]

Originally Posted By: 05foresterXT
In the summer time, the only time I could get a read where the oil sat on the "full" dot was when the engine was "cold." As soon as the fall temperatures started setting in, and we had sub 40 degree nights, I noticed low reads in the morning. I never thought that the oil would shrink to less than it was when I bought it, but at this point, it seems that is the only likely place it could be going. The "hot" dipstick readings have remained consistent from when I first filled the engine with oil.


Here's my take on it from years of experience in fleet management and my own personal vehicles. My personal vehicle tends to stay in a heated garage. I check it when "cold," that is, before I drive it for the first time for the day. The garage never gets colder than 10 C, but can be over 30 C in the hot summer. That's not a huge spread, and provides for fairly consistent readings, based both on temperature and the vehicle sitting exactly the same each time. From your post, you're indicating you want consistent readings.

Considering your sump temperature's "cold" readings are subject to wilder swings in temperature, a reading at operating temperatures may be the best way to get consistent readings. In the fleet usage, the oil never got "cold," that is, never to ambient temperatures. They were always checked when hot, after being shut down for five minutes. It's not perfect, but you may be stuck with such a method if you want to get consistent readings.

 

[Jim Allen]

Originally Posted By: 05foresterXT
I keep seeing people mention "hot" and "cold" as if they are the only two temperatures that exist. The point of my original post was that I'm interested in whether my car is still consuming oil or not.

In the summer time, the only time I could get a read where the oil sat on the "full" dot was when the engine was "cold." As soon as the fall temperatures started setting in, and we had sub 40 degree nights, I noticed low reads in the morning. I never thought that the oil would shrink to less than it was when I bought it, but at this point, it seems that is the only likely place it could be going. The "hot" dipstick readings have remained consistent from when I first filled the engine with oil.


Sounds like you found the source of your apparent problem. Here are some generalities with regards to oil consumption that follow along with things a dealer might ask you to do if you complained of oil consumption on a warranted engine.

Step one is often to do an oil change, fill the engine with EXACTLY the amount of oil specified run the engine, likely to full warmup, let it drain down and check the level to get a baseline. Sometimes dipsticks are off (tubes not driven fully in, etc.)

Tracking oil consumption requires some methodology and consistency, i.e. checking the oil in as close to the same conditions as possible each time. Hot is easier to do because "cold" might 30F or 60 F and you could see slightly different levels at each of those temps.

One question to ask is whether you top off? Generally, you shouldn't add oil until it's at the add mark. Why? Some engines will really slurp up that first half quart and if you keep adding, it keeps slurping and you perceive high consumption. BUT, if you leave the level alone, apparent consumption will slow way down after that top half quart is used.

If you have trouble reading the dipstick, you might try applying some paint to it. It has to be a high temp, oil resistant paint (engine paint) and allowed to fully and completely dry before putting it back into the engine. Paint only the area between add and full. Color... whatever you thing will enhance reading the stick. Bear in mind that white worked great for me at first when I did this, but the white turned brown after a while. Not sure if all paint does this but... FYI.

 

[cp3]

Interesting, I have never heard or thought of this consuming the first certain amount of oil before. Maybe I will try not topping up and see what happens. Any idea what would be the cause of something like this?

 

[Tom NJ]

Originally Posted By: Jim Allen
If you have trouble reading the dipstick, you might try applying some paint to it.

Another approach that works for me is to rub the dipstick hard and repeatedly with a paper towel to get it very very dry. This seems to give a better read.

Tom NJ

 

[45ACP]

Originally Posted By: Tom NJ
Originally Posted By: Jim Allen
If you have trouble reading the dipstick, you might try applying some paint to it.

Another approach that works for me is to rub the dipstick hard and repeatedly with a paper towel to get it very very dry. This seems to give a better read.

Tom NJ


Use the holes. They help, particularly when the oil is almost invisible. I hate new oil for that reason, btw. I add sn additivea just so i can see the level right after an OC.

 

[OldCowboy]

Originally Posted By: Tom NJ

Use the holes. They help, particularly when the oil is almost invisible. I hate new oil for that reason, btw. I add sn additivea just so i can see the level right after an OC.


What is sn additivea?

 

[SteveSRT8]

additivea: many types of additives in a particular group used together!

 

[45ACP]

Originally Posted By: OldCowboy
Originally Posted By: Tom NJ

Use the holes. They help, particularly when the oil is almost invisible. I hate new oil for that reason, btw. I add sn additivea just so i can see the level right after an OC.


What is sn additivea?


Return of the Latin language. Motorus Oilum Deus, Espiritu Santi. Additivea Syntheticum, Deos Pluribus Unum. Mobilus, SOPUS, Penzolium. Unum.

Use the holes. They help, particularly when the oil is almost invisible. I hate new oil for that reason, btw. I add an additive just so i can see the level right after an OC. It gives it some color.

 

[bluesubie]

Originally Posted By: Eddie
My Forester has two full marks. There is a line to show add & full at cold or normal running temp and a hole to show the max HOT temp level. To answer your question, yes, oil does expand & contract depending on the temp. There is no minimum contraction in the absolute sense. When the oil cold it should be between the full & add marks and when hot, the max should not exceed the second hot mark. I think this is explained in the owners manual which is a good read. Ed

This!

Although, I believe the max hot level is marked with a notch instead of a hole. If it's above the notch at anytime when hot, it is overfilled. I do check my oil when the car is cold but SoA does say to check it at every fill-up

-Dennis

 

[bluesubie]

And if you don't have an owner's manual, you can sign up for my.subaru.com to access it.

Quote:

Checking the oil level

Check the engine oil level at each fuel stop.
1. Park the vehicle on a level surface and stop the engine.

2. Pull out the dipstick, wipe it clean, and insert it again. 3. Be sure the dipstick is correctly inserted until it
stops with the graphic symbol appearing as shown in the illustration.

1) Notch 2) Upper level 3) Lower level

4. Pull out the dipstick again and check the oil level on it. If it is below the lower level, add oil to bring the level up to the upper level.

If you check the oil level just after stopping the engine, wait a few minutes for the oil to drain back into the oil pan before checking the level. Just after driving or while the engine is warm, the engine oil level reading may be in a range between the upper level and the notch mark. This is caused by thermal expansion of the engine oil.

To prevent overfilling the engine oil, do not add any additional oil above the upper level when the engine is cold.


-Dennis