Okay, nationalize the oil companies- for example like Saudi Arabia, Indonesia and Mexico- what have you gained?
Iran is a member of OPEC and very happy with that. Iraq will return in full to the OPEC fold. Not that it matters, the oil price is set by supply and demand.

Indonesia and Mexico to an extent subsidize petroleum to their citizens, but this lowers government income. Venezuela subsidizes oil to Venezuelans, and may make a deal with Morales of Bolivia, but sells at market prices to everyone else.

Iran and Iraq are members of OPEC, and seem happy with that, letting supply and demand determine the income they get (or will get) from their petroleum exports. Lower prices might be offered to their citizens, but doesn't help to secure lower prices for anyone else.

Bolivia is showing signs of breaking up under Morales' rule.
Both Chavez and Morales must modify their 'neoleftist' agendas or they will be ousted. They have little effect on the world stage.