Rotate .out log files

1) If you are using nodemanager you can redirect .out to .log and control them via console (server -> logging tab under console)
traverse to */user_projects/domains/base_domain/bin/nodemanager
take a backup of wlscontrol.sh and edit it
change OutFile=$ServerDir/logs/$ServerName.out to OutFile=$ServerDir/logs/$ServerName.log

ELSE

2) You can make changes to the OS parameters under /etc/logrotate.conf
add the below lines at the end of the file

<Location of logs directory>/*.out
{
copytruncate
rotate 4
size=20Mb
}

ELSE

3)Add the flag  -Dweblogic.log.RedirectStdoutToServerLogEnabled=true to redirect .out to .log and control them via console (server -> logging tab under console)
and if you are starting via nodemanager add below additional parameters
nodemanager.properties under */wlserver_10.3/common/nodemanager
StartScriptName=startWebLogic.cmd
StartScriptEnabled=true

ELSE

4)Use OS command "logrotate" (via cron) to achieve your target. You can combine it with copytruncate to rotate logs.
http://linuxcommand.org/man_pages/logrotate8.html