For Whirlcool:
Very old powder detergents may not fully dissolve when used, as witness my old 1950's "all" powder in the blue & green box. If you wish to use such old powders, try dissolving the recommended amount in a small container of hot water(or nuke it) before adding it to the washer. When I had my older top-loaders, I used to always measure my liquid & powder detergents and let them dissolve in the tub as the water fills, then add clothes when about 10" of water was in the tub. I got the very best performance from them, with never any residue whatsoever.