I've been out of antique bikes for many years now, but every once in a while an old friend or customer drags me back in. I have to do a service on a "4" and I can't remember what kind of oil to use. Being it doesn't touch the clutch, I'm tempted to use a modern synthetic multi-grade. Thanks in advance.
Hard to imagine that anything back when this thing was made is as good as a synthetic multi. I could be wrong. I think they call for straight 30...maybe 50... But anything written in my books will be from 75 years ago. So...what are the guys who actually run these things actually running?