There you go arguing again...
Just because someone has a different viewpoint than you, that does not mean they are arguing, nor does it mean they are wrong. It certainly could mean you are intolerant of anyone who would dare pose a viewpoint different from yours - thus you lash out with personal affronts against them. And that's sad.
I agree that grease would be the proper medium, but it would be difficult to employ properly in these miniscule situations.
I agree that grease (depending on type and viscosity) would be better. But disagree it would be difficult to employ - unless you are afraid to get your finger greasy. LOL
It is simple to "pack" bearings or a bearing chamber with grease. You just scoop a blob of grease onto your finger and squish it in there until full, then be done.
Oil that you apply by dripping "drops" from a can is the wrong lubricant for a fan that is not sealed - unless the fan is designed for that type of lubricant. And computer fans are not. Plain and simple.
Why?
Gravity. Computer fans (either case, GPU or CPU fans) are not sealed tight. And they are designed to be mounted horizontally (with airflow pointed up or down) or mounted vertically in desktop or tower cases. If your lubricant will "run" or "flow" down when a drop is applied to the side of a vertical surface like a mirror or refrigerator, it will run or flow (or be flung) out of the bearing chamber of the fan simply because those chambers are not sealed.
If your lubricant is stored in a bottle or can and you "pour" (or drip) that lubricant out of its container, the viscosity is too low to be used effectively in computer fans - at least not for very long. That means motor oils, ATF fluid, 3-in-One oil and similar "fluid" type lubricants are the wrong type. Those bearings require high viscosity (thick) greases, or very thick oils that are NOT affected by gravity. That is, lubricants that cannot run or "work" their way out of those unsealed bearing chambers.
Motors that truly are sealed often use low viscosity lubricants simply because that lubricant cannot escape. There are no openings through which it can. A sticker over the fan hub of a computer case fan, or CPU cooler fan is not a true seal. It is essentially, just a dust cover.
Any lubricant is better than none. But that does not mean any lubricant is the right lubricant for the job.
They all spin faster using a special grease. few more rpm 5-10 extra
The goal should be "smoother", not faster. Faster may be a side benefit if friction from inadequate lubrication and/or uneven wear was already slowing the fan down. Generally, fans are designed to spin at specific speeds depending on the voltage applied. The goal should be to ensure they spin freely, and not "grind" away from friction.