Most of you might remember that after I installed my new battery, because I found the original about bone-dry, I was going to pull this new one every two years and top it off with distilled water. As this winter marks that two-year period I pulled it, opened it up and found it was already more then 1/4" below the top of the plates. This was not good. Glad I decided to do it. Was thinking about going one more year but had nothing else to do. I went a head and gave them a little extra...so maybe they would last another two years.
So...not a bad thing to add to your maintenance schedule. Should add years to the battery's life. Just be careful and take your time taking the cap seal off.