Flash point, base oil quality, performance

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Originally Posted By: IndyFan
Would flash point in a used oil analysis be a more accurate snapshot, since it is one sample of oil, complete with all additives, (albeit used)? In other words, when I look at a UOA from my engine, is the flash point measured from that sample accurate? I know it won't relate to the flash point in the virgin oil, obviously because of use and contaminates, but maybe it is a useful number to tell how that specific oil in the engine held up?


I don't consider any single run flash point to be accurate. A Closed Cup flash point (ASTM D 93) can be useful in determining fuel dilution in used oil, but not how well the oil held up. The more common Cleveland Open Cup (COC) method used for virgin oils may miss some or all of the fuel.
 
This thread is an excellent example of why we should just pick a name brand oil that meets the specs for our engine and be done with it. Only a handful of people on this site know even the first thing about oil, the other 99.999999999% is just noise.
 
Originally Posted By: Tom NJ
Originally Posted By: Virtus_Probi

What time is lunch? I'm all for some fresh produce...
;^)
Sounds like you have found new ways to be productive in your retirement!

Retirement is so busy that I don't know where I ever fund the time to work! Been growing vegetables for over 40 years, just on a larger scale now. Lunch is beet salad with onions, blue cheese, and walnuts. Better hurry over!
Oh, and I brew beer!
cheers3.gif


I hated beets when I was kid and love them now. It's just a bonus that they are quite healthy.
Would have had to pass on the beer on a work day... ;^)

I forgot to bring lunch and was at my desk for the noon hour, so it was cheap junk from a vending machine just to keep my hunger from distracting me. Unsatisfying and unhealthy!!
 
Originally Posted By: SlipperyPete
This thread is an excellent example of why we should just pick a name brand oil that meets the specs for our engine and be done with it. Only a handful of people on this site know even the first thing about oil, the other 99.999999999% is just noise.

Pretty much.
 
Originally Posted By: Virtus_Probi
I hated beets when I was kid and love them now.


Me too. Made a big pot of borscht!

Originally Posted By: Virtus_Probi
Would have had to pass on the beer on a work day... ;^)


What's a work day?
wink.gif
 
Here is a good thread on a similar subject: https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4676508/Flash_Point_and_NOACK

Good correlation between flash point and volatility across different brands with different base oil types and additives appears to be weak. With same brand and same base oil type and same formulation strategy of not using dumbbell blends OR using dumbbell blends in similar proportions, correlation appears to be potentially decent.

I expect terrible correlation between flash point and base oil quality.
 
Originally Posted By: Tom NJ
Originally Posted By: OilUzer
How did Noack came up with 250°C?
Or who came up with 250C?I

Do we want the Noack test temperature (250°C = 482°F) be above most (all?) oil flash points to be an effective test or does it matter at all?


I don't know who decided on 250°C - hopefully it was correlated to some real world performance parameter as all tests should be, but I have also seen what I call "management by round numbers".

Noack and flash point are quite different. Noack evaporates the light ends of an oil by blowing air across the surface at a constant 250°C and measures the weight loss of the sample. Flash point slowly heats the oil from ambient to the point at which the vapors give a flash when a flame is passed over. The flame is not applied until the oil is within 27°C of the expected flash point, so much of the light ends are already evaporated off. If you added say 5% of a solvent to an oil, the Noack loss would go up by 5% since all of the solvent would be evaporated off under the conditions of the test. The flash point, however, would not be affected since the solvent would be evaporated off before the flame is passed over the oil surface.


Thank you!
Interesting that the flame (ignition source) is not applied until within 27°C of expected flash point! I was under assumption (my own ... lol) that the ignition source is always present.
what happens if the vapours ignite immediately when the flame is applied! Is the "expected flash point" lowered and rerun the test (at the new expected minus 27°C) or I am assuming again that by now the flash points are so figured out that this (immediate ignition) will never be an issue.
 
Also what if the ignitable vapours were present and gone by the time the test gets to expected minus 27C.
Wouldn't th e test miss that? Hence my assumption that ignition source is always present.
Maybe you already answered that. Need to read everything again.
Thanks
 
Originally Posted By: OilUzer
Interesting that the flame (ignition source) is not applied until within 27°C of expected flash point! I was under assumption (my own ... lol) that the ignition source is always present.
what happens if the vapours ignite immediately when the flame is applied! Is the "expected flash point" lowered and rerun the test (at the new expected minus 27°C) or I am assuming again that by now the flash points are so figured out that this (immediate ignition) will never be an issue.

No, on an open cup test you swing the flame above the (open) cup and look for the flash. On the closed cup test there is a trap door that opens as you rotate the flame down towards it. Again you listen/look for the pop. If it ignites well before you expect then either the substance under test isn't what you think it is or you rerun the test at a lower temperature.

Again a test that has applicability to characterize a particular component but I struggle to see how it relates to the finished oil. Much like pour point you're only testing how it performs in that specific piece of ASTM test equipment so you can qualify a material. It doesn't (and doesn't have to) relate to anything specific to ICE operation.
 
Originally Posted By: OilUzer
Also what if the ignitable vapours were present and gone by the time the test gets to expected minus 27C.
Wouldn't th e test miss that? Hence my assumption that ignition source is always present.
Maybe you already answered that. Need to read everything again.
Thanks

No you keep going until it does ignite. But this again illustrates how it has limited or no usefulness for a finished oil. For characterizing octane? Yes. A particular molecular weight PAO? Maybe. But a finished oil with many constituents? I don't see how.

You do understand that it isn't -27 C right? Your wording isn't clear.
 
Thanks kschachn. As far as "how it relates to the finished oil" ... I am not sure either.
grin.gif
I wasn't thinking along that line.
when I see a test or a problem or an argument that I am interested, my head tries to analyze/solve or improve or find flaws ... not under my control, However I don't hear any voices yet. lol
 
kschachn, I realize that Tom was saying that the ignition source (fire) is applied at approximately "expected flash point" minus 27°C ... and not -27°C
 
Originally Posted By: OilUzer
Also what if the ignitable vapours were present and gone by the time the test gets to expected minus 27C.
Wouldn't th e test miss that?
Thanks


Yes it would miss it. I have seen flash point material boil and then stop well before the flame pass starts. If a flash occurs with the first pass of the flame the test must be repeated.

The test is terminated when a brief flash appears on the surface of the oil. If you continue the test until a flame is sustained for five seconds after removing the flame, you have the fire point.

We used the test as a quality control test to assure that the esters were properly stripped of any volatiles during the manufacturing process, although a good old sniff test was actually more sensitive. It rarely shows up in an industry specification.
 
Originally Posted By: Tom NJ
We used the test as a quality control test to assure that the esters were properly stripped of any volatiles during the manufacturing process, although a good old sniff test was actually more sensitive. It rarely shows up in an industry specification.

Very appropriate for an ester I think
smile.gif
 
Originally Posted By: SlipperyPete
This thread is an excellent example of why we should just pick a name brand oil that meets the specs for our engine and be done with it. Only a handful of people on this site know even the first thing about oil, the other 99.999999999% is just noise.


Sounds like you haven't found your oil yet!
grin.gif
 
Originally Posted By: Tom NJ
Originally Posted By: Virtus_Probi
I hated beets when I was kid and love them now.

Me too. Made a big pot of borscht!
Originally Posted By: Virtus_Probi
Would have had to pass on the beer on a work day... ;^)

What's a work day?
wink.gif


Touche'!
I'm glad that you are able to take time away from enjoying your garden to share your knowledge on this forum...and to hear that you keep so busy in retirement.

I remember being absolutely horrified when the father of a Russian friend of mine pulled a jug of borscht from their fridge and took several big chugs from it...I could see doing that myself now, except I would probably be mindful of backwash and put it in a glass or bowl. ;^)
 
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