issue seems to come up a lot despite the fact that its covered
pretty well in the manual. Its not helped by the fact that
BMW has changed the sight glass and the methodology a few
times since the introduction of the modern oilhead twin.
properly check the oil, leave the bike on the centerstand
overnight. Check it first thing, before starting the motor.
The oil level should be within the red circle around the
perimeter of the sight glass. Some RTs have a red dot at
the center of the sight glass indicating the optimal level.
Basically, if the oil is within the red circle, you are
good to go.
the oil is low, add only a small amount at a time. Remember
that It takes a long time for the oil to flow down
to the sight glass, and its a common mistake to keep adding
oil until a change is observed in the sight glass. If you
do this, you will put in too much oil and possibly damage
the engine. So WAIT - I usually give it at least 20 minutes
to seep down and stabilize before checking the sight glass
and adding more oil.
you are concerned about oil level or consumption while riding,
a good way to check while the bike is hot is to put the
bike on the side stand and check the sight glass. The red
circle should be covered almost solidly in this situation
- at least 2/3. If there is no oil in the red circle, then
you probably should add some. Again, only add a small amount
at a time.