I have my dh clean & oil after every queensize quilt. In between I clean (brush out) bobbin area every time I change bobbin. I oil once or twice a week on visible easy to reach areas. My singers are 36 & 52 yrs young. DH unscrews all screws and gets inside to keep them clean & lubedricated. I live in the desert. My sewing machine doctor said machines dry up faster here then in more humid climates.