side curtains...what to use...

[hippie]

Hey men, I tried cleaning my side curtains today and they just will not get clean. I'm cleaning the window part and no matter what I try they continue to have an oily coating that I cannot get off. I tried a drop or two of dish soap in warm water but that does not cut the oil off the windows. I need something stronger to cut through the oil but not that strong that it ruins my windows. Does anyone know what to use? Thank you, Bob