Well you say that but they label it as 'Abbey Silicone gun oil' - it's 100% silicone though, so it's cool. Just slightly misleading name I guess.
To OP: Just to put your mind at ease, whilst Abbey is kind of tailored towards airsoft players and pellet gun enthusiasts, it is good stuff. The problem with grabbing some from a hardware shop is most have additives that eat away at the seals in your gun. The Abbey stuff is about £6 a bottle, but that bottle will last you a couple of years so it's not a problem.
You can also get spray cans of the low-viscosity silicone oil, but really you don't need to worry about complicating matters with that. Some high-viscosity silicone oil will do the trick in 99% of cases.