There is quite a bit of difference between that bike and a post 1970 airhead.
They do not have and oil filter, like ours (the turn signals are the least of your worries!).
Instead, they have metal slingers on the crank shaft that throw the oil to the points that need lubrication.
The slingers have small holes in them, and over time they fill up with sludge.
This is accelerated by not changing the oil often enough, but it is still considered to be "regular" maintenance.
Problem is, to clean the slingers, one must remove the crank. That is a complete tear-down of the engine.
If you are a young man, and have the money, I would buy it and have it rebuilt (if it hasn't already [
documented!]) and plan on keeping it forever, and depending on how many miles you put on it, you may need it done 2 or 3 times in your life.
If you are an older man, and have the money, I would buy it and have it rebuilt, and it will probably outlast your riding years.
And that is just the slingers.
They are wonderful, beautiful bikes, and I would love to have one.
The closest I have been is a 1969 R60US for a couple of years, as the ex's first bike, and then I built a conversion for pulling a sidecar. I loved the sidecar rig. I have learned a lot since 1984 when we owned the US model, that would have come in handy back then. All hail the internet!
Boxerworks has a section on their forum dedicated to the '55-'69 years.
They are off the air right now while they change internet service providers.
No doubt there is a Yahoo Group, as well?
This is the Vintage BMW Motorcycles, Inc.
http://vintagebmw.org/version6/