I have a Janome also (a Horizon) and there is no word of oiling. However, after a couple hundred hours of sewing, my husband, sitting in the other room, said, "Honey...are you sure that thing doesn't need oiling...sounds like it does." I said, "I don't know, the book doesn't say anything about oiling."
Hmm...So, he took the sewing machine oil and found places where he thought it could use it. And yes, it helped how ti sounded.