OEM european power steering fluid (15-851OEM)

Appearance: green colored light liquid

May be similar to CHF 11S. Reported here 11S should be compatible with HNBR/NBR:

https://forums.mercedesclub.org.uk/index.php?threads/abc-valve-block-rebuild-pics-is-this-right.138407/page-2

SRAM oring tested in fluid:

• OD swell 20% after 24hrs (10->12mm)
• Thickness seems unchanged
• Caliper seal thickness did increase ~10%, enough to make it unusable

SRAM oring should be EPDM. So maybe 851OEM oil has very similar compatibility to standard mineral oil?

NBR oring:

• No swell

VQM (silicone):

• No swell

https://forums.mtbr.com/brake-time/o-ring-material-question-680609.html