Hello Tiger, Your dishwasher is designed to use rinse aid for good drying performance. Without rinse aid, your dishes and dishwasher interior will have excessive moisture. The Heat Dry and ProDry™ options will not perform as well without rinse aid. Rinse aid improves drying and reduces water spots and filming. Water "sheets" off dishes rather than forming water droplets that cling and leave spots. Rinse Aid can also help your dishwasher retain less moisture on the interior walls and door. It could take up to 2 weeks of regular usage for the new dishwasher to reach optimal drying performance. We hope this helps!