Originally Posted by
cubewheels
You can safely use grease for any sealed bearing / bushing because the seal will keep dirt and dust away.
Grease will be a better choice for sealed bushings for reducing wear.
Because your years of experience tells you so? Oh, wait.
Sealed bearings have seals. If you force grease into them, you might carry grit in with it. And if you take it apart to regrease them, you may very well destroy the seals so they are no longer sealed.
There is also the fact that bearing races and to a larger extent, bushings which can be made from a variety of materials, and some react to some types of lubricant (grease or liquid - that is: Some swell up with petroleum products or whatever), so it's not really that clear cut as you make it out to be.
I swap out my sealed bearings if they suddenly dry up. Because if they do, the seals are not working.
Anyway, a derailleur pulley is not sealed.