Absolutely, you can consume sugar that’s 20 years old. Sugar, if stored properly in a sealed, dry container away from moisture and contaminants, is safe to eat even after a long time. However, over extended periods, sugar might clump or harden due to moisture absorption, affecting its texture. I once used sugar over a decade old; although it was clumped, it didn’t cause any harm. Just break up the clumps or soften it if necessary. Nonetheless, always check for any unusual odors, changes in color, or signs of spoilage before using. In general, sugar is safe for a significantly extended period if stored correctly.