You are talking about the inside of the bolt, right? Grease is what you want. White lithium will get gooey/sticky after a while (like a year), so you'll have to open it up, wash with dishsoap and warm water, then relube. I used to use it then went with Gunslick's Anhydrous Graphite lube, works great (especially on GBB slide rails), and is cheap (but hard to find). AEG gearbox lube, like teflon grease or silicon grease, is pretty much the best you can go with.
And just because I asked, don't grease the outside of your bolt, it'll collect dirst, sand, bits of cedar leaf, etc. and bugger up your action. Others have asked about this (which is why I brought it up), and I tried it myself once, is just a big don't do. Spray it with a dry lube such as dry graphite or teflon spray, or even just rub a big pencil lead all over it.