dbms_audit_mgmt.init_cleanup seems to require a lot of space in SYSAUX

Hi,
Strange issue:

We have a 11gr2-database which has auditing on. This results at the moment in a AUD$-table of 13GB and over 70 million records. The table resides in the SYSTEM-tablespace and has to be moved out from this one.

With

PROMPT creating purge job: First initialize the cleaning

begin

   dbms_audit_mgmt.init_cleanup(

   audit_trail_type            => dbms_audit_mgmt.audit_trail_all,

   default_cleanup_interval    => 7*24 );

end;

/

this should be done.
Although SYSAUX is on autoextend and can grow to 32TB (exadata-machine) it nags about insufficient space:

ORA-46267: Insufficient space in 'SYSAUX' tablespace, cannot complete operation
ORA-06512: at "SYS.DBMS_AUDIT_MGMT", line 1039