I adjusted the rear brake calipers for the emergency brakes to work properly, but during the adjustment a little bit of brake fluid came out (not uncommon as I understand). I wanted to add the amount I believe escaped during the adjustment back to the brake fluid reservoir. When I opened it, I saw 2 compartments inside it. The one on the right (see pic) has noticeably dirtier fluid in it than the one on the left. Can someone explain to me what those are? Also, if I am adding some brake fluid to it, which one should it go to?