Dishwasher - Stubborn Stains
If your machine doesn’t get the dishes clean all the way, run the hot water at the sink until it gets warm before starting the dishwasher. This will help the first wash water cycle to have hotter water. If this doesn’t work, perhaps you need new nozzles.

Dishwasher - Use
It does not matter how many dishes you place in the dishwashing machine, the same amount of water and energy are used. Therefore to be more economical, run full loads at all times in the dishwasher! By air drying you will also save, by avoiding the drying heater from running.