1999 BMW 323is Q&A

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

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 also some gunkie yellowish substance on the cap itself. A few weeks ago I had to have the tensioner pulley and V belts replaced. What is wrong? -
Answer 1
The belts have nothing to do with it, possibly a leaking auto trans oil cooler and the red fluid if ATF. Good luck -
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What would cause a reddish oily looking substance in my expansion tank along with coolant level being extremely high?