If you have a warm place to work, sounds like a great time to do a brake fluid flush and change. No worries about mixing
How does the pad thickness look? 1/3 down on fluid with no leaks points to a fair amount of pad wear.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.