I oil my Bernina with every 3rd bobbin change. I clean the feed dogs and bobbin area each time I change the bobbin. I take it in once a year to be serviced. As for my Featherweight, I really take that machine apart and oil every place that needs oil. I also use Singer grease on the gears. Since I use the Featherweight daily, I service it once a week. There are so many places that need oil on the Featherweight that I use a check list and check off each place as I oil it.