why does the antifreeze feels greasy and has milky texture/color? on 2003 Audi A6 Quattro

I think some oil is leaking into radiator. What would caused it? How big of job is it to fix it?

2 answers
Several possibilities , trans/oil cooler in radiator has failed and leaking oil into coolant , or headgasket/cracked head issues. What other symptoms/problems does the vehicle have?
ziptie is right take to grage i hear that they have head gasket problems.