Just a high level question and response since we don't want anyone having to write a book for us.
What are seal compatibility test requirements and how is it tested?
Also how many different seal materials are out there (e.g. fancy cars vs. what I drive) and to what extend or % are the seal materials the same?
To meet for example API SP, is it just on paper that it (seal compatibility) was taken into consideration and based on xyz chemical reactions, this oil is compatible with majority of seals ...
Or a real test running in an engine and/or abusing the seal for 5,10,20,50K miles? Or experience gained over decades with the material so it can be rubber-stamped?
Another Q:
As an example, iirc one of Audi tests (Part of A40?) require a track test which is a rigorous test that some others may not conduct or at least not to that extreme. Are there other more extensive seal compatibility tests relative to SP for example?