Rub fairy liquid directly onto the stain and rub it in. Leave it for a good while (a day if possible) and then bung it in the wash. I've never spilt baby oil but I have used this method to remove cooking oil spilt or splashed on tshirts
i remember splashing grease from cooking onto a top some years ago and i used brown paper and then ironed over it a few times until it lifted off, if i remember right it did take quite a while to get it off, but did so eventually. give it a go but start off with the iron not too hot then turn it up gradually, hope its successful and good luck.