oracle free sysaux tablespace

select dbms_stats.get_stats_history_retention from dual;

exec dbms_stats.alter_stats_history_retention(10);

--delete old statistics

exec DBMS_STATS.PURGE_STATS(sysdate -10);

further info:

http://www.informatik-aktuell.de/betrieb/datenbanken/der-oracle-sysaux-tablespace-reorganisation-und-verkleinerung.html