low PH oils

[pirestani]

dear friends;
What PH limit (acidity)in oils to be caused by high temp. is harmfull for internal copper winding of hermetic compressors?and how can we easily find out (define) the amount of chemical damage?

[superheat]

Are POE oil systems less sensative to acid, because the oils are more acidic to start with?

[pirestani]

I think so . but i mean thats a general qustion.
How much PH in oils may not react with copper inside compressors?is there any research about that?
thanks you alot.