The only thing you oil on a newer model Bernina machine is the hook race & only 1 drop. Older models did require oiling in a few other areas, as they were all metal inside.

As for the feet, lint gets in the movable parts, causing the squeaks. A good cleaning should fix it right up. My one Bernina walking foot is 28 years old & still going strong. NEVER put oil on any plactic parts, as it can cause damage.