I was an industrial mechanic for several years a long time ago so I have always oiled mine just because I knew it was needed. All moving parts on any machine need some lubrication at some point in time. But I also tear it down (sort of speak) once a year and do a complete cleaning and oil job. I have a Singer Touch & Sew that is probably about 35 years old or older. Works like new and I don't think I will ever get rid of it.
Oh yea the special machine oil they are talking about is called machine oil ( I use the "3-in-one" brand myself) which you can get at any hardware store.