Two other caveats: One, Is it an AWC or an S3C? Consumer Reports found the S3C could go out of adjustment in a way which not only left you without power but also left the sprocket uncoupled from the brakes.

Two, How is the C/B itself lubricated? I am not too sure about old sturmeys. I think I got plenty of extra workout riding around in the winter with a c/b because the ones with steel pads are designed to be grease lubricated. The pads run pretty close to the hub and what with the grease being cold, you will have plenty of drag. This isn't the same as hub bearings because they're not rolling. You have two big, flat brake shoes inside a turning hub, maybe half a millimeter from it, constantly shearing a layer of cold, thick grease.

I relubed my Nexus with oil and it was too thin. The c/b made a horrible scraping noise and I found it was deeply scored when I took it apart to regrease. So you can't depend on oil if it's designed for grease.