Once it's well seasoned, you can use a bit of dish detergent occasionally for a big mess like the seared scallops we had tonight. Normally, never soap. Hot water and a nylon scrubby pad, and wipe dry. The only time I ever have to re-oil is if there are several big messes in a row requiring detergent. Maybe once a year. We use cast iron every single day, and for over 90% of stove-top cooking.