So I'm doing a thermostat change and I drained the coolant from the radiator in preparation. The coolant that drained was green - like original, green IAT stuff. If I'm not mistaken, that's not right for this car? I've got quite a few BMWs and have the blue BMW/Volvo HOAT coolant lying around - I called my tech and he said that was fine to use. But I didn't realize at the time that the car had green stuff in there - and from my understanding, IAT and HOAT should not mix. So what the hell do I do? lol Do I go back and drain the block as best I can (which won't be everything), or can I just go and buy some of the original green stuff and keep using that until I go to the shop later this year for the belt service and just have him do a complete flush then?