Alternatives are WD-40 or petroleum jelly (Vaseline), however the oil in it will dissolve or melt plastic. So if you don't want to ruin your cube then stay away from WD-40 or Vaseline
I really recommend Silicone lubricant either spray types like Jig-a-loo or CRC. I, and most speedcubers, personally like oil type silicone like Lubix or Traxxas 50k DIff Oil. These two are really the same stuff in terms of performance but I would go for the Traxxas 50k Diff Oil as it is only $8 for 50CC while Lubix is $14 for only 2CC. Why would you pay more for the same stuff? Check out www.bestspeedcube.com/speed-cube-lubrication/
for some info on speed cube lubrication.