All the info here fits with what I know and have heard, especially about avoiding oiling the electronics and throwing a plastic machine away when it breaks. I'd also like to add that in an article written by a sewing machine repair guy he specifically said that manufaturers tell owners not to oil their machines because many owners would oil everything including the belts, and since belts work by friction few things work more poorly than an oiled machine belt. I've also never heard of sewing machine oil damaging plastic or nylon gears.
Maybe you could use it in it's great functioning but noisy condition until it acts up then carefully oil it to see if you can get it working again?