i blew up my transmission.. i have never heard of the fluids mixing.. its was lack of maintance by trhe orignal owner. i payed $400 bucks for a rebuilt transmission with 100,000 miles and changed it in my driveway. i also added a 12,000GVW transmission cooler.. truck goes great. also i have the knock sensor code and that wouldn't cause transmission problems. hell my selenoid for overdrive went and im still running it. gotta love nissan.