ASTM test / determining miscibility of motor oils

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Thanks for sharing that...

I raised it here
https://bobistheoilguy.com/forums/ubbthreads.php/topics/3503628/Re:_The_oft_quoted_ASTM_D6922

and reference back to it in threads, and get met with "of course" two Sn rated oils mixed meet all the SN standards, there's a "compatibility test".

Just means that they can be mixed, cooled, heated and cooled without splitting or blowing chunks...with the reference oils that is.
 
I know, there's a lot of confusion concerning this. But if you're not a bitoger, this information will never get read. The average joe will only see, "compatible with all other oil", as seen on the labels. But technically, however minute, a risk does exist.
 
6 reference oils are used for mixing with the test specimen. Therefore, how can it be said that the oil being tested can mix safely with all the permutations of different manufacturers? PQIA tests the oils of dozens of producers/blenders. I guess all that can be said is that it passed this particular test with those 6 specific ref oils.
 
Originally Posted By: 69GTX
6 reference oils are used for mixing with the test specimen. Therefore, how can it be said that the oil being tested can mix safely with all the permutations of different manufacturers? PQIA tests the oils of dozens of producers/blenders. I guess all that can be said is that it passed this particular test with those 6 specific ref oils.


Exactly. There would be no way to test the infinate ways different formulations mix.
 
When it comes to motor oils, miscibility is absolutely the lowest of any of my concerns.

I have yet to hear of any real problems.
 
Originally Posted By: Linctex
When it comes to motor oils, miscibility is absolutely the lowest of any of my concerns.

I have yet to hear of any real problems.


I've posted before the couple of SAE papers where REAL problems occurred, with PPD and VII interaction causing failures to pump at what people would consider fairly benign temperatures.

Has happened, is fairly rare, and the "W" rating is the most likely thing to be affected. And if you REALLY need that W rating, then you don't want to mix.
 
Yeah that is a great point Shannow. If one really needs their 5w to truly be thin enough to pump at -22°F then it really matters a whole lot. If one lives in Orlando Florida where it may get down to 32°F then it doesn't matter no where near as much.
 
Exactly. I already hit that temperature once this fall. In Orlando, not so much.
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