The internals of an airsoft gun mechbox require lubrication, these lubrications come in the forms of greases and oils. Your houp rubber never requires any lubrication, in fact spraying silicone oil into your hopup will probly mess up your accuracey for a while.
The only real places inside your gun that need lubrication are your gears, your bushings, and a intcy little bit around your cylinder head.
Silicone oil is used primarily in gas guns, more specifically gas gun magazines. The oil helps keep the seals inside the mag from drying out.
"Its only a little bit on fire"