The oil generally leaks into the cooling system on the 103 because of the design and pressure. As said above, transmission fluid is red, not brown. If it is oil, you'll need to get a head gasket job done asap. If you are handy and inclined to DIY, search my name for my rebuild thread. You may want to get a compression test done...it should indicate it.

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k