We never used to with our old machine but we recently got a new one that has a warning light telling us to run a machine care program every so often. I looked at the Bosch website and it's £8.82 for 3 sachets of powder. The cheaper ones (Lidl etc.) seem to be liquids. I wondered whether running it empty on the care program with some white vinegar would achieve the same. The dishwasher doesn't smell and is normally used every other day.