Well... HS33 has 5years warranty.... and there have write in Manual > NEVER USE WATER...
Water dont preserve the internal cables... and have a lot things mixed... (or you will use Destilled water?) like fluor, minerals, ...
People that I know use another Oils Mineral
like
But Royal Magura Oil isnt expensive.... dont have sence buy something like $80... and no wanna buy OIL from $20... for make some economy, for lose 5 years warranty... >.<
is like buy bike Trial from $1300, and no use Helmet from $40 =P