Here is a list of South American countries that do not have Spanish as an official language. Some of these countries speak spanish as a common language though, even though it's not official:
Argentina
Brazil
Chile
Falkland Islands
French Guiana
Guyana
Nicaragua
Suriname
Uruguay
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It is more similar to South American countries, but it is a
North American country
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Ecuador and Venezuela are the two South American countries that are members of OPEC (Organization of the Petroleum Exporting Countries). They are also the only South American countries that are full members of the organization.