What's the best oil for a pocket knife?

put only edible oil on it! a knife is used to cut food, it's useless if you sprayed toxic products on the blade.

I'm sure this has been pointed out here before, but I'll say it again: WD-40 is a solvent, not a lubricant. Use it to loosen a rusty bolt. If you want to lubricate and/or protect something, use oil. Mineral oil works quite well for blades.

A single drop of 3-in-1 oil works wonders. Half a drop if you can manage it. I have also used sewing machine oil and hair clipper oil with great success. One drop should last 6 months. Any lighter oil will just evaporate.

+1: Food grade mineral oil so I can use it to cut food. It never sits long anyway.

Sentry Solutions makes a lube that drys completely and works great.

I've been using Victorinox Multi Tool Oil for quite some time on all of my folding knives/tools. http://bit.ly/Ana0JT Comes in a small handy container. Lasts for months. One drop on every hinge is all you need.

I primarily use stainless steel pocket knives as my every day carry knife. As such, I don't need to worry about oiling the blade. I still do sometimes (out of habit), but I don't need to. The knives I get tend to have good bearings/swivels as well and don't need much maintenance. On my carbon steel blades I use a variety of oils. For display/heirloom/investment knives I use break-free clp. I've never found a better way to keep guns or knives from corroding. For other knives, that I might end up eating with or using, I use mineral oil or 3-in-1. It's a rarity when I use one of them for food, so I'm not worried about a little 3-in-1. It builds character.

Silicone lubricants would probably work well and they won't likely cause an oily spot on your clothes.

White Lightning is a liquid lubricating wax I've used before. It's great, dries and stays, won't leak off into the material of your clothes and lubes nicely. I've been working on the same bottle for about 8 years!

CLP as mentioned above is great for all around use but not food grade (as also hinted at above). People love to crap on WD40 but it's a great water excluder so if you plan to lube frequently and it's what you already have it's fine and you'll have zero problems. Large amounts of anything liquid will only attract crud to your pivot, so using a q-tip saturated in your oil of choice is a nice way to control application.

For purposes of of lubricating the hinges of pocket/folding knifes/tools: I have had good luck using "M12 Kellube". See http://www.dawsonprecision.com/ProductDetail.jsp?LISTID=CF0001-1095452308

Kellube is intended for use as a gun lubricant. I claim, based on the extensive testing that gun lubricants receive and the similarity of the lubrication/dirt resistance requirements for gun and knife hinges, that this type of lubricant is ideally suited for this purpose.

Prior to applying the lubricant, use some sort of compressed air (e.g. Radio Shack Dust Remover Spray) to "blast-away" the dirt & grit that has accumulated in the hinge. Use only one very small drop of lubricant per hinge side. The thin needle applicator on the Kellube container makes this easy. A 1 oz. container may last the rest of your life.

I have been using a "dry" bicycle lube with good results. I use Finish Line Dry Teflon, but there are many others. My thinking is that a "wet" lube like mineral oil and WD-40 will pick up pocket lint and grit, which will eventually suck out the oil and leave the joint dry. A dry lube is designed not to pick up that junk. You can get it at any bike store; just ask for a dry lube. Just a drop or two will last a long time, and the stuff is cheap.