Permatex Dielectric Grease (made for spark plug boots and battery terminals) has worked for me for years as a budget silicone grease and it’s never caused harm to any of my o-rings, but as stated who knows what they are made of.
I got some Oatey silicone plumbers grease which is supposed to be almost pure but it’s not thick enough for me.
I’ve used Slip 2000 EWG (grease) in a pinch.
BTW, i’ve put different types of o-rings in seperate ziploc bags, saturated each with these lubes and left them for 2+ years (still in there actually), and cant tell a difference between them and the control samples stored in the open at room temp. The only o-rings i have in the bags that i am certain of the type is Viton for what it’s worth. The others…who knows what they’re made of.
Tidbit: The dielectric grease is also good for light bulb sockets, super thin layer on the bulb threads helps prevent seizing :+1: !