Strangely, that's the solution I always used ;-) Either that of set the date format to J, and you'll get all your dates back in Julian format (as numbers) which makes it really easy to add and subtract them. You just can't display them easily.

For the other half of your comment, you've probably mixed up to_date and to_char: to_date converts from a string to a date value. to_char converts from a date to a string value.
SELECT TO_CHAR(sysdate, 'DD-MON-YYYY HH24:MI:SS') FROM DUAL returns 12-AUG-2002 15:48:23

--
Tommy
Too stupid to live.
Too stubborn to die.