Every sewing machine needs oil in some places. When the dealer says not to oil they intend for you to bring it back for a check up once a year and that is when it gets oiled. I have a Bernina and have watched the tech do a cleaning. The machine gets a good oiling. Machine oil is made to evaporate so it doesn't gum up inside the machine. Many of the machines have embedded silicone that releases when the machine is sewing. It's not good to let those machines sit without use for a long period of time. I have a Janome Jem and the bobbin gets a drop of oil every so often.