[L473ncy]

It's sold under the name "RC Shock Oil" at RC Hobby stores (make sure to ask if it's 100% silicone oil).

You'll want something like 10 or 15 wt. oil (or 5 wt. if they carry it but in my experience not that many places do). The AI silicone oil is supposed to be 1.5 wt. but you can't get that as a regular consumer, that stuff is for commercial applications or so I've been told (you basically have to buy an entire "barrel" of that stuff at minimum is what people tell me (~160 Litres)) so you have to buy it from AI themselves (since they package it into smaller packages that are useful for consumers instead of a big barrel worth of oil that will never be fully used unless it's for an entire field that only runs GBBR's).