Mig wire storage question

Hi guys, i am wondering what you guys and gals suggest as far as storing your Mig wire on the machine. I have a small welding business on the go and do mainly small jobs like trailers and the like but dont weld everyday, sometimes i go weeks without a job so my question is, is there any tips or tricks to prevent the wire rusting or deteriorating while in the machine when not in use? I thought about giving it a spray with WD40 but im concerned about contaminating the wire and subsequent welds.