You were taught correctly, but how hard is hard? Try it some time. It only costs tranny fluid to try it. My 68 would go sideways about a foot or two from 1st to 2nd floored and that was with Dextron. With type F fluid it was bone jarring. Racing maybe, not for me in a street car. I'll not try it again.
Are you talking about a stock transmission doing that? Did you install a shift kit? I've used "F" for a long time and never had that experience, both with stock & transmissions built with modified innards.
