I need to replace my radiator in my '02 530i. I live at leat an hour away from the nearest dealer and am pretty sure the radiator has a trans cooler set up. My question is the trans oil; Is it only the ESSO oil that the dealer told me over the phone about or is there a compatible oil I can top off my system with and not have any issues down the road. This will be my first repair on this vehicle and I didn't buy a manual yet any help would be appreciated.