With a D4172 of 0.7 mm, a D3233B TLV of 1200 lbs, a kinematic viscosity of 2.8 cSt and a surface tension lower than many of what this readership consider to be top-shelf penetrants, what make WD-40 Multiuse Product a poor lubricant and a poor penetrant? It also displaces moisture and is a good rust inhibitor.
I'm only trying to understand the thinking behind the opinions of WD-40 MP. I am doing a commercial study of the performance of and market for penetrants and lubricants.
I like it for a coating on things just starting to rust although it doesn't last a long time. I also like it for when I want to lubricate, but I don't want it to stay there. I put a very light coat on my new spark plugs a few days ago because I wanted to aid in installation but I didn't want it to hang around like antisieze, etc. For all I know it won't dry off but I think it probably will based on how I've seen it disappear over time on things.
When I was a kid, I kept my plastic fishing worms coated in it. Looking back I can't believe it didn't repell fish, but it didn't seem to hurt my fishing.
I mostly use it to soften up old, hardened grease that's too gummy for the application, as a temporary fix till I get a chance to clean and relube.
I used to use it to get sticker/label/tape goo off of things, but decided it's just as effective and lower cost to use 1 cent worth of 2 cycle gas premix instead. Really it's not even 1 cent worth because I save leftover from one season and don't want to put it back in the equipment once months of winter have elapsed, and can also use it for parts cleaning.