I think it' s actually silicone oil, but you have to be careful to stop it getting into metal to metal joints, where it definitely doesn't do any good.
I used to use it a lot back in the heady days of the 1970's. A couple of drops down the transfer port used to work well in my old Airsporter.
Nowadays I avoid it like the plague. I try to get the piston tube polished/burnished with a layer of moly disulphide and add the merest hint of Abbey SM50, which may or may not have silicone in it, I''ve never been able to be sure on that.
Keep the metal to metal joints lubed with 3in1, Ballistol - whatever, something that says "Gun" on the tin is probably best.