Co-workers Town and Country... He opened it up and said trans filter is very clogged. So, he wants to flush it, but can't pass fluid through plugged filter. Does he need to waste a filter for the flush then change it again?
Don’t do a flush. Simply replace the filter and fluid and leave it at that. Repeat again in another 20k miles.
Too many horror stories of fluid flushing on these transmissions breaking loose the gunk inside and gumming up the works. Some have resulted in requiring a complete tear down of the tranny to clean it out.