We did the Oracle 64 bit ODAC install (ODAC121021_x64.ZIP contains setup.exe) when logged in as the ServerName\Administrator. Then OraOLEDB.Oracle appeared in SSMS -Linked Servers - Providers. This was in MS-SQL server 2014 64 bit running on Windows Server 2012 R2 64 bit. The same install done earlier by me logged in as my domain account (I'm an administrator on the machine) had OraOLEDB.Oracle not appearing.