I have those same white spots on my old and very healthy jade plant. After reading that this might be scale I Immediately took chucks advice and removed the spots with a cotton swab and some rubbing alcohol and sent my husband off for neem oil. In the mean time I have been researching these white spots on jade plants, and it seems quite common for jade to have a salt residue on the leaves that looks just like the photo and what is on my plant. This also wipes clean with a cloth. I'm no pro with plants but there may be another issue with your jade plant.