i'd go with a/c leak as it needed to be regassed intially and the oil/dye is a yellowy colour, and your anti freeze is probaly blue, stick your head under the bumper and have a look and you'll probaly be able to see, get a drip on your finger have a sniff if it smells like your coolant resevoir it's your rad hose or your rad my rad on my 16v started leaking (no drips yet though), if it dont the only other thing at the front is your a/c condenser and pipes to it