Back in the 90's, I would occasionally put one drop of liquid dishwashing soap on the door of my RR Maytag in addition to regular automatic detergent in the dispensers, and it did actually help clean oily/greasy items better without suds-locking (hard water). However, that machine would fill with probably 3 times the water than modern machines therefore was much more diluted. Start out with one drop, then monitor throughout the cycle.