1999 BMW 323is Q&A

1999 BMW 323is Question: red oily substance in expansion tank

What would cause a reddish oily looking substance in my expansion tank along with coolant level being extremely high? -
Answer 1
It sounds as if you have transmission fluid mixed in with your coolant. If the internal transmission cooler (usually built in with the radiator) has sprung a leak, its pumping transmission fluid into the radiator and mixing with the coolant. -
Comment 1
I'm sorry if you've gotten this more than once. My computer is acting up. Is it safe to drive my car with this leak and trans. fluid in my coolant? I have a 2.5 hour drive home. -
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I am leaving town and just checked my coolant to make sure I had pleanty. When I took off the cap, the coolant was all the way to the top and a reddish oily substance is floating on top. There was ...