Mineral oil was used effectively in the past in INDOOR STORAGE BATTERY applications where old style chargers could boil off the water. It is unnecessary today in those applications and as others have pointed out...destructive to battery capacity in moving and tilting application where the plates WILL become contaminated...or frozen destruction northern climates.
I still disagree with the notion of leaving ANY kind of charger...trickle or modern 4 stage... plugged in and running for many weeks or months unattended. Simply charge the battery to 100% and you are good for 90 days at least if you simply disconnect the negative wire. Self discharge in even VERY warm climates is 10-15% a month. I had a friend in Maine who left a fully charged older battery sit from January till September when he remembered it....it still had about half its' charge as I recall. You won't get that in FL or AZ...but 90 days should be a no brainer.
2015 Georgetown 280DS
2014 Vespa LX150 2014 StellaAuto 125