I'm curious about all of these sprays - the US SDS for this spray basically says it's two propellants plus naptha and a neutral oil (presumably that neutral oil won't cure). The spray here is about $16 a can, which is convenient, but is it better than mixing naptha and mineral oil in a spray bottle?ACF50 is what I use now, especially on cast iron, it's particularly good for long-term storage, since using it on my planes about 3 months ago there's not even a hint of rust.
WD40s MSDS suggests (I'd need a chemist to know if any of these dry - neutral, i'm assuming means that they don't react with much) it's a hydrocarbon (1/2 - taking the place of naptha) and then a combination of petroleum oils - about 25%, and kerosene/jet fuel - about 15-20%. Presumably, WD40 is made intentionally of an oil that will oxidize or change and form a film (as it does), though it's hard to know if that's on purpose, or if it's a matter of just not having as clean of oils as some other sprays.
Neutral food safe mineral oil in the US is about $16 a gallon, and mineral spirits or naptha are probably about the same.
Interestingly, the eye-wateringly expensive "trend honing fluid" MSDS showed a slow-evaporating naptha and petroleum oils (sort of a theme developing here) - and somewhere they added something that makes it look blue. Smurf, I guess.
I don't use WD40 on everything as I don't think it's probably as touch safe as mineral oil, but I've not had anything with mineral oil rust (and went to that after realizing that camelia oil seemed like it was being sold by woodworking retailers solely because they could charge the same for it in 8 ounces as food supply supplied food safe machine mineral oil (for meat slicing lube and cleaning) for 128 ounces. And the mineral oil doesn't start to set up in the fall in my shop.