As we can see in the changelog there should be an entry which automaticly clears the tmp folder, but there is no entry.
Changelog shows this new feature for OG 1.6:
"feature: Added a cron event to clear tmp folder."
Also the cron logs in my case are not stroed in the "tmp" folder, they are stored int the "root" folder, i dont now why, but it would be a good idea if the folder is selectable and the filenames (with asterisk/wildcard) too, then every user can automaticly by event deleting the cron logfiles as he want/needed.
Regards Claudio