How do I lubricate a noisy fan?

I have a case fan that can be quite noisy. I can take the fan out of the case, peel back the sticker on the center to expose access to the bearings, and lubricate the fan. Thus far, I've been using a few drops of WD-40, but after a few days the fan makes noise again.

Obviously, I could buy a new fan, but knowing how to lubricate a noisy fan seems somewhat useful, as not all hardware hardware has replaceable fan units.

Does anyone know why the WD-40 only works temporarily, and what I should be using instead?

I'd try 3 in one oil. WD-40 is mostly a solvent, 3 in one should give you a longer term solution.

You should really replace the fan. The ball bearing has probably seized and adding lubrication will only help for a few days. As a temporary lubricant you could use about anything with low friction.

Aerosol Teflon is another option.

I do what you're suggesting quite frequently. I put a few drops of WD40 down into the bearing, and then I use a high pressure air hose to spin the fan real fast. I then take a paper towel and wipe out the gunk. I might repeat the process one more time. Then I put a drop or two of 3 in 1 oil in there and give it another good spin.

After having done this dozens of times with fans of various size and make, I would say that it restores fan life for a considerable period. Sometimes the fan will start chattering again after a year or so and I'll repeat the process. In only a few situations have I ever had to buy a new fan. It's not that I'm cheap, it's that finding a replacement fan can be an irritating process..especially if it's some goofy chipset fan with a unique mount. This process only takes ten minutes, and so far I've found it less time consuming than trying to find a replacement.

One exception I make is for power supply fans. I don't open those things up anymore. I typically just buy a new supply.

Clean it out and use a vegetable based oil with a pin hole oil lubricator. It looks like a pen. You can get them at a hardware store. Or just replace the fan you cheapo.