Volkswagen Repair: Oil In water, laundry detergent, vw passat

Question
My 2003 VW Passat 1.8T has Oil in the water but no water in the Oil. The vehicle got hot in traffic and the STOP warning light flashed. I turned the heater on and the temp went down. I opened the hood and I found oil in the water fill tank but I did not find water in the oil. I think it may be the oil cooler, what do you think?

Thank You for You're help.
Kirk Staggs

Answer
Hi Kirk;
Yep.
Don't mean to be terse, but I think you're right.  Happens, some.  New cooler, and flush the hell out of the entire cooling system with laundry detergent, and rinse, again, and again, and again.  Change the oil too, and get a new VW filter, along with the new cooler...27, or 28 mm socket...fairly deep to get the cooler nut off.  The hoses will be a screaming match!  Good luck.