I know that this thread is old, but I thought I would go ahead and add my two cents of bad experience for others to be forewarned in case they have a similar experience. I actually bought a round trip ticket, originating from the United States to leave on August 30th (2011) and return in May of 2012. Upon check-in, United gave me crap for having the duration of my stay exceed the 90 day tourist visa limit without having the "appropriate" visa. They wanted me to pay to change my flight to November! I told them this was unnecessary as I could renew the visa by leaving and re-entering the country. Not their responsibility to make sure I have the appropriate visa, it is mine! I asked to see the manager and she went to look it up in the rulebook. "If you're a student, then you meet the requirements for tourist visa extension." Well, I graduated from college 5 months ago, but they don't know the difference, and they finally gave me my boarding pass. Of course, when I got to Argentina, they didn't ask me a single question, just stamped my passport.