I would use Mobil 1 synthetic 5w40. It seems to work the best for me.
The 2004 Volkswagen Passat has double overhead cam (DOHC).
The Volkswagen equivalent antifreeze is the RED antifreeze known as Dexcool. Do not use the green or blue or any other type or you will be looking for trouble.
R134a
You may use Volkswagon G12 coolant or Prestone Extended Life coolant. If cost is a factor use the latter.
The 2007 Volkswagen Passat has double overhead cam (DOHC).
The 2010 Volkswagen Passat has double overhead cam (DOHC).
The 2009 Volkswagen Passat has double overhead cam (DOHC).
The 2013 Volkswagen Passat has double overhead cam (DOHC).
The 2014 Volkswagen Passat has double overhead cam (DOHC).
The 2012 Volkswagen Passat has double overhead cam (DOHC).
The 2008 Volkswagen Passat has double overhead cam (DOHC).
The 2003 Volkswagen Passat has double overhead cam (DOHC).