With both my long arm and my commerical (upholstery) machines I do oil if they have sat more than just a few days and allow to run for a short time before sewing (so any excess oil get absorbed). My DMS hardly goes more than 2 days without being used, but I do have a few that sit and they will at least get oil in the bobbin race. Almost any kind of machine (not just sewing) that sits for long the lubricant will pool at the lowest point and that is not where you want it when you turn it on.