Dale :
I assume you mean a Arkansas oil stone. The best think to do is keep it clean use plenty of oil norton brand from the home depot works well. I have uses instrument oil but is harder to come by and more expensive. Wipe off the dirty oil after each use.
smiths recommends cleaning with soap and water after each use. scrub with a nylon brush.
and yes occasional lapping if needed to true them.
I have a couple stones that I have had for years I just use plenty of oil cant say I have ever used soap and water on them.
How I clean and renew my stones (we cal them slips) is take a piece of scrap steel and a dab of lapping compound and lap the stone it will remove a small amount of stone and remove any material stuck on the stone, then a good cleaning with some denatured alcohol. After oil it back up and you are set with what should be and preform as good as brand new.
Thanks All Some good idea's . I would be afraid to use water because it freezes were I live . I have always wondered about this so I through I would ask . Again THANKS to ALL Dale
Being a Joiner by trade not a metal basher I leave my stones on the window cill and the odd day it is not raining in the UK and we get the yellow thing in the sky I find the warmth tends to make it sweat and it brings any deposits up to the surface, I then re oil with 3 in 1 oil a light machine oil, but this just help keeping it clean, not flattening for as you all know a good joiners stone is always flat . Yea !!!