My sunnysky 2204 motors have been going maybe 100-150 batteries now, and a couple of days ago, I started to see vibrations when flying, and they are getting worse for every flight. 2-blade props are almost unflyable, and 3-blade is better, but still a lot of vibrations. the mid range throttle is the worst. I can feel that there is endplay in the bearings on two of the motors and a little bit on the third one. the fourth is fine. I have not had any major crashes with these motors yet.
So the big question is? How long does these bearings normally last? Can they be replaced with new ones like these:
http://www.readytoflyquads.com/house-mot...04-bearing

The Bearings you listed will work, but remember to buy some C-Clips as well, http://www.readytoflyquads.com/c-clip-fo...r-shafts-5
As to how long bearings should last...Hard to say really, depends how much dust, dirt, water whatever has got to them. But 100 to 150 batteries worth is pretty good. While you have the motors apart, check the magnets and shaft, also worth checking the windings by eye for obvious damage and great time to clean everything as well.

A tip to help keep your bearings in good order is get a small syringe and blunt fine needle tip and apply a drop of oil to them (Singer sewing machine oil works really well).

What I do is after flight session I used compressed air (via a spray can and tip if in the field ) or my compressor at home and blow the motors clean of dust , sand , grit, or even a smallish paintbrush to get the crap out and then apply the oil. Never use the likes of WD-40.

Agree about WD-40.  It's not a lubricant, but a water displacement agent that has some lubricating properties.  What about a synthetic oil?

If you are thinking about synthetic motor oil, I would not recommend it because it has too high viscosity. In theory this can give more friction, so the motor will need more power to spin. That is why you should use a low viscosity oil like the sewing machine oil.

You could probably use a automatic transmission oil also

Do you know if that is true with all synthetic oils?  What I am thinking about is the same oil used lube model railroad motors.  It's pretty thin and I am a little concerned about it's resistance to brake down due to high temps.....

Synthetic oils are in general much better than mineral oil, with an ability to keep its specific viscosity over a larger temperature span. But it is essential to get an oil that is good for what you want to use it for. I would say that a type of synthetic oil would be best. I'm not sure what kind of oil you have, but if it is for model trains like marklin or similar with fine mechanics, I would guess it is good for these bearings

Thanks for the response.....sorry for taking so long to respond (been busy hunting Easter eggs...among other things). Guess the only way I'll know is to try it. : )