Depending on the safe and location you store them , look at getting a Golden Rod too, it circulates warm air inside the safe . Its almost a must have .
I use Montana Xtreme products, but most stuff on the market will work fine. I check my guns in my safe weekly ,I know its over kill but its a piece of mind. I do try to re-apply oil / clean them every 3-4 months unless they go to the range.Its worked for me , I wish you luck.
Steve