The oiliness is really not apparent in your photo. Can't tell what it is from this.
How much head space do you have in your secondary vessel? There should almost none (if a carboy/gallon jug, fill it right up into the neck). There's really not a lot of activity in this vessel, and there needs to be very little headspace. Oxygen in headspace can promote bacterial/fungal growth (which may or may not be the case, here). Top off with more cider or apple juice.