Synthetic Oil for Passat?

What is your question?

A mechanic advised me he only uses Mobil-1 Synthetic oil because it best for engines. He said Pennzoil creates a film and Valvoline gets foamy, but of which are bad. My Passat has 121,000 miles but I am currently only driving a few thousand miles per year, some months only 150 miles. He said at that rate, I can change the oil only once per year as long as I change the filter every six months. Is all this true? If so, is it worth it to spend $80-100 for this once per year oil change?