i forget what coolant is acceptable and what will tear up the system. But i always play it on the safe side and use bmw coolant. You can order it from bav auto for about $17 a gallon, but remember that you dilute it 50/50 with water so every gallon of coolant equals two gallons in the car. It is really not too expensive. Not near as expensive as it would be to replace parts that could get damaged from using the wrong coolant. I am sure that someone else know what coolants are acceptable for the system and which are not. Search the forum and i am sure you will find your answer.