Does anyone know the thermal expansion of engine oil, say like 15W40???

The specific gravity and density API is listed on most of the oils product sheets .

Are you asking about the fluid level showing high when up to temperature ?

Yes I was wondering about the fluid level showing high or low at different temperatures...

15°C 0,858 4,00 0,00
20°C 0,855 4,01 0,35
40°C 0,842 4,08 1,90
60°C 0,828 4,14 3,62
80°C 0,815 4,21 5,28
100°C 0,802 4,28 6,98
120°C 0,789 4,35 8,75
140°C 0,776 4,42 10,57

line 1 = °C
line 2= density
line 3 = volume in liter
line 4 = volume change in percent

This is an example of a 5W-40 oil

I suppose that it changes with every time of oil as well......

From 15C to 100C the 5w40 increased 7 percent in volume. While my motorhome is running 10w30, it may be similar and would help explain why I can have the oil at the correct level (checked cold) and then check it later (good and hot) and it seems to be grossly overfilled. It normally takes 6.5 quarts, so it could be about half a quart more hot.

Off topic. Is it that outside the U.S. decimials are indicated with a comma (this 0,01 instead of 0.01)? At first I though folks were having typos, but it seems to be a pretty consistent usage. And then how would you express one million and one hundredth (1,000,000.01)?

Well, I made a minor mistake - I wrote lines - but meant colums.

And yes, In Europe decimals are indicated as a comma.

1.000.000,01 would be the European way of writing your example.

I did some experimenting with 15W40 and found that from -40C to 125C the oil actually expands by almost 13%. First I calculated and then did an experiment. Both showed relativly the same results. I could not believe just how much the oil actually expanded......

quote:

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Originally posted by Callisa:
1.000.000,01 would be the European way of writing your example.

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One could get quite confused with numbers like:

7.345

2,023

quote:

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One could get quite confused with numbers like:

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Just a matter of convention and what you are used to know. Not more or less.
Believe me, I am always in trouble with non-SI units like pounds, square inch etc.