Pour Valvoline into a transmission, shift into gears and get the feeling of it. Then drain about 2 quarts, and pour 1 bottle of Royal Purple. Then compare. It will leave with the person saying "Ahhhh, that's so smooth." It will be better if its not mixed with other oils.
I have it on my S14, so does my little bro and Vang. This stuff is magic, feels like there's no fluid in the tranny. Cost only $25 to fill up the tranny, but I'll pay more to have it.