It would depend of what you mean when you say old; if you want to list (for example) the files that have been modified thest last 2 days (2 days as an example) you can play with the find comand by this way:
ls |find -mtime -2
Where mtime would refer to the files/directories that have been modified the last two days.
Otherwise there is no way to check the "creation time" of the file, unless you have named with an informative name to the log files; names such as log_date; in that case you can play with a grep in order to show you the wished result.
As we are talking about logs, is better to store them (and check the necessary ones) instead of deleting them.