guy I work with just returned a lemon A3 Jetta to Carmax who wouldn't give him his money back but did apply his payment to another car of his choice. so he picked out an A4 Jetta. Looks and runs great but after driving it for a while it's got some serious mayonnaise on the underside of the oil fill cap. He drives about 15 miles each way to work and claims it gets fully hot on each trip. I suggested possibly either a blown head gasket or else maybe a malfunctioning PCV valve. anything else that could cause this?
thx
nate