i'm having a hard time believing your ultimate inferno "died" after 30 games. my ultimate inferno has over 500 games on it and thanks to daily cleanings, trips thru the rejuvenator, and resurfacings/rescuffings/resandings it rolls like new.
anyway, my goliath has been wetsanded as coarse as 120 grit and as smooth as 4,000 grit. at 120 grit i couldn't find enough oil to hold this ball. 220 grit was still more than enough.