As Tony already stated, the following:
wntaccessadd("", "C:\Oracle", "Authenticated Users", 303, "Dir2K:Modify")
Is effectively executed as the following:
wntaccessadd("", "C:\Oracle", "Authenticated Users", 300, "Dir2K:Modify")
As described in the help topic for the wntAccessAdd() function.
The pre-defined access string, "Dir2K:Modify", equates to the following:
"0:3:1245631"
Please note the ACE flags value of "3" in that access string. It indicates that the ACE that is being added should be inheritable by all subfolders and files, the the underlying Win32 API function that is used to set the security on "C:\Oracle" being responsible for propagating all inheritable ACEs to all subordinate objects.
Inheritance can be blocked by setting the "Protected DACL" flag on the security descriptor of a directory or file, so that is something to investigate. Another thing to verify is that the process executing the script actually has been granted access rights to modify the permissions or is running sufficiently elevated to do so via usage of LSA privileges.