I've never noticed that on my own car but I haven't had to change my brake fluid out yet, if I was to take a guess it's likely a dedicated fluid is for the ABS system or overflow chamber as you suggested
Let me check the SM though and see what it says, I'll update my post with the findings.
Hmmm I don't actually see anything in the SM that covers the reservoir itself in any great detail, I'm starting to lean
towards the fact it's an over-flow chamber and you just need to bleed off the old brake fluid.
I'm sure someone else will chime in here, but if not maybe give the dealership a call and have them confirm.
2009 G37 X - Blue Slate - Michelin X-Ice 3/ Michelin AS/3+ Location: The Great White North
Planned Mods: Takeda Stage II Intakes, Borla Catback Exhaust,
G-Stop SS brake lines, Megan Racing Upper Strut-Tower.
“Passion rules reason, for better or for worse.” - Terry Goodkind
Last edited by BigHeadClan; 09-11-2019 at 11:20 AM.