What version of oracle oledb did you install?
Apparently there is a networksetting "TCP window scaling" that might be the culprit:
See Oracle support document Oledb and Odbc 64 Bit On Windows 2008 and Windows Vista Have Bad Performances [ID 1264980.1]
or Intermittent Slow Oracle Net from Windows 7/Vista/2008 machines[/url]
Not a solution, but what time takes
Select ku_id, TOT_DATE from SIIY where TOT_DATE > 12252012 on the oracle side?
Is TOT_DATE a date or a number? If date I would expect where TOT_DATE > to_date('12252012','MMDDYYYY')
in openquery you have to double the '
*added version of oledb, networksetting TCP Windows Scaling