Hi all, A friend has a 90 735i, IN which he doesn't use any coolant!!!!, he says use Coolant only for 3 months in the fall, and drain in late winter and the next 9 Month month with only water!!!!. I told him he should not do this, since I have always use the BMW coolant IN MY 735I-88!!. He says it is nonesense, he uses standard cheap antifreeze coolant. His car really runs very nice. WHAT DO YOU GUYS THINK ABOU THIS??