Any oil will work. Mineral oil. 3-in-1. WD-40 (sorry haters). Mobil 1. Ballistol. Break-Free CLP. FP-10. Tuff-Glide. Militec. And the really expensive stuff too. Its fun trying this stuff and seeing how it works for you. I almost never apply oil, and don't really see a need to. Maybe a drop when I reassemble a knife, or on the extremely rare occasion that it feels or sounds like it needs it, but that's it. There is a little variance in lubricity and how long they last before re-application is required, and a lot of variance in price. But they all work pretty much the same. In some knives, like CRKs, the right application of the right lube (CRK lube or Finish Line Extreme Fluoro) can help the knife open like butter, but in most knives I don't really think it matters much what you use. Maybe try something like Ballistol or Break-Free CLP as a good mid-cost option, unless you just have a hankering for going economical (mineral oil) or spendy (Nano Lube at $43 per ounce). As long as your 0566 flicks open smoothly, you have picked the right oil. It will probably do that just fine even if you never put a drop of oil on it, though a drop of oil sure doesn't hurt. This is just my take on things, and its worthy remembering that I have no idea what I'm talking about on this subject or any other.