my 2 cents ...leaving a perfectly good working trans enclosed eliminates 2 other factors in trans failures(also applies to all things lubricated) the dealer concerned with profits using cheap fluid(or broadspectrum) instead of the high tech correct stuff(yes unfortunately there are too many choices) and the mechanic getting contamination in the once sealed unit. I too would like proof that frequent changes work. Really I am still on the fence, what failed first the lube or the part quality? was it the chicken or the egg?