My Bernina (and yours too) has a built-in stitch counter. When it gets to a certain number of stitches (180,000???) the display tells you it's time to oil. However, I never rely on that stitch counter. I clean and oil frequently, more often if I'm using one of the lintier cotton threads. I generally check the area for lint with every bobbin change, and oil with perhaps every 2nd or 3rd bobbin. Some machines don't require oil, but these do, and putting it off until you take the Bernina in for service would definitely not be a good idea.