Without falling into an oil debate, no cycle mechanic I’ve ever spoken to uses or would recommend wd40 for chain oil. It’s far too thin and is primarily for freeing stuck parts and cleaning. It’s not meant for long term lubrication - it dries out or get washed off almost instantly.
3 in 1 is fine, but the main advantage of a proper chain lube is that they don’t attract grime and dirt as quickly
Waxing (also possible with bee wax) once you streamline the process (chain link, hot water for cleaning, cheap wax warmer the one women use and since the new chains (every 5000-10000km) are heavily pre-lubed you need 3 steps to remove the mineral oil: 1. soak in gasoline or alike for 1 day, 2. degrease and then 3. finish it off with white spirit) is imo the best for the chain.
Clean and smooth. I rewax every week (200km), takes me 10 min in total, also a a convenient way to inspect and adjust my whole drivetrain, regularly.
WD40 is absolutely a lubricant. The WD40 is not a lubricant thing just needs to die already. Of course it’s not the best lubricant for every job. In fact it’s probably not the best lubricant for any job, but it’s a good enough lubricant for many jobs. It’s also a penetrant and water displacer. Versatile products usually aren’t the absolute best choice for a given use case, but that doesn’t make versatility bad.
I think this is part of the love for the machine, and is a part of hacker culture I find endearing even if it's not necessarily rational. I'd put tweaking your Linux windowing system into the same category :)
