INSTR with Date value

SQL> CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
  2                        ENAME VARCHAR2(10),
  3                        HIREDATE DATE);

Table created.
SQL> INSERT INTO EMP VALUES (1, 'SMITH', TO_DATE('17-DEC-1980', 'DD-MON-YYYY'));
SQL> INSERT INTO EMP VALUES (2, 'ALLEN', TO_DATE('20-FEB-1981', 'DD-MON-YYYY'));
SQL> INSERT INTO EMP VALUES (3, 'WARD',  TO_DATE('22-FEB-1981', 'DD-MON-YYYY'));
SQL> INSERT INTO EMP VALUES (4, 'JONES', TO_DATE('2-APR-1981',  'DD-MON-YYYY'));
SQL> INSERT INTO EMP VALUES (5, 'MARTIN',TO_DATE('28-SEP-1981', 'DD-MON-YYYY'));

SQL> SELECT empno, INSTR(hiredate, 'FEB')
  2  FROM emp;

     EMPNO INSTR(HIREDATE,'FEB')
---------- ---------------------
         1                     0
         2                     4
         3                     4
         4                     0
         5                     0

SQL>