My raditior has this think think milkshake looking stuff in it. It's is a very light color brown in it. Now I know it's not a blown head gasket cause it just passed smog with flying colors. It has never over heated before I notice and even now it still does not over heat. I notice have poured some sleat in the radiator just in case. I have just replaced the fuel pump and just two days ago replaced the radiator. Now water reserve still looks the same it looks like a milkshake still and I just notice now the radiator is leaking water. What next right!!! What is wrong with my car, can anyone help me please ???