Chapstick (lip balm).
Taken from ibanezrules.com:
"Gummed up knives. Alot of people believe that you should oil the posts and knives. Personally I've never seen any improvement by doing this but what I do see is the oil collect enough dirt and crud to literally gum up the works. Use your wife's toothbrush to clean the crud off of the posts and knives. On the other hand I have seen great improvement on trem return using Chapstick [for the folk offshore that a lip balm product sold in the US and many other countries, it has a very waxy-greasy feel and does work quite well at improving free return to neutral]"
Jimmy
P.S. Edit your location (state or country).