Well I dont know what year windstar you have but on newer models windstar i believe 98 to 2003 transmission fluid goes into the power steering so you use red transmission fluid (mercon v) in both the transmission and power steering. I would check the power steering fluid level to see what it is at the van does not need to be running to check this. Then check the tranmission fluid with the van heated up and in PARK. The level should be to the very top of the hash marks or even higher. Since you had a blinking OD light I suspect your transmission fluid is leaking. | 
