water-based, silicon-based or oil? I'm talking about lubricants. I know that that the usual kind like astroglide usually contains glycerin which can cause irritation or worse. I'm getting this for a provider friend. That's why I'm asking. Favorites? I've already done some research and I understand that the silicone-based lubricants have a different feel than the water-based ones and that preference is personal. Each has advantages and disadvantages. That's another reason I'm asking.