- Jul 13, 2011
For a knife, the only thing I'd use WD40 for is to oil an oil stone. There are much better options for both joint lubrication and surface corrosion protection.
I use WD40 (Water Displacement, attempt number 40) only as a cleaner to remove gunk and remains of glue from knives and other stuff.
For pure lubrication of moving parts i've never come across anything better (and longer lasting) than Nano-Oil, 10 weight for most folders and 5 weight for ones that have very tight production tolerances.
As usual, Bill DeShivs is right. Look up the MSDS sheets for just about any fancy lube, and the actual lubricating ingredient is likely to be... mineral oil in one way or another. From Fluid Film to WD 40 and beyond. Sometimes they thin it out with solvents, sometimes add tints or aromas, but mineral oil is a pretty good lubricant, cheap and its properties well known. So it ends up being hard to avoid.
There are special oils that won't attack some kinds of rubber or plastics. These might be of some use in particular instances. But those instances are rare in the knife world. Knives don't generate enough heat or operate under extreme pressure levels to break down oils. Even the most high tech knives tend to be really simple mechanisms.
I've advocated avoiding lubrication, unless absolutely necessary. I have several knives that don't need it, and thus don't get it. I have in the past lubricated knives prophylactically, only to find that, if anything, lubrication just encourages contaminants into the pivots and wear surfaces, making a nice little slurry that can dry out/goop up and cause more wear and sluggishness than had it never been used in the first place.