BMW R 1200 RT Rider's Manual page 110

If the lower edge of the black
8
bellows in the brake-fluid reser-
voir is below the MAX marking:
108
Checking front brake pad thick-
ness ( 104).
Checking rear brake fluid
level
A low fluid level in the
brake reservoir can allow air
to penetrate the brake system.
This significantly reduces braking
efficiency.
z
Check brake fluid level
regularly.
Make sure ground is level and
firm and place motorcycle on
its center stand.
Removing driver's seat (
Read off brake fluid level at
rear brake-fluid reservoir 1.
The brake fluid level in the
brake-fluid reservoir drops
due to brake pad wear.
72).
Rear brake fluid level
Brake fluid DOT4
The brake fluid level must
not fall below the MIN mark.
(Brake-fluid reservoir hori-
zontal, motorcycle standing
upright)
If brake fluid level drops below
permissible level:
Have the defect corrected as
soon as possible by a special-
ized workshop, preferably an
authorized BMW Motorrad re-
tailer.