I think the case of no-oil machines is only because of the delicate electronic parts, they are susceptible to oil spill. I'm not sure what they do to make them lubrication free; the first explanation I was given years ago was they use teflon embedded plastic, it's super slippery and doesn't need it. More recent info I have found is that new machines store the lubrication in the joints and hinges, as a reservoir. When the parts are in motion the oil will dispence around the parts, and return to it's place when the machine rests. These joints need a refill now and then and that's where an anual service comes in. Noone really dares to mess with a brand new Bernina 770 or a Husqvarna Ruby, but I doubt lower to medium priced machines have those fancy reservoir joints and hinges (I'm not really sure what they call them). The makers give us very little information, everything is very limited to a few phrases in a manual.