Oil Changes

I'm new to this board and signed up today 5/26/05. Need to know what type of oil I should used in my A4 1.8 auto. Also I need to know how often I need to change my oil. I hear a dozen of different opionions from other sources and don't know what to do. I'm guess I need to use synthetic oil although its incredibly expensive. If I did used synthetic oil can I change it after about 10k instead of 5k? Please help anyone!