Again, John, see my post above. Type F is "grippy" (less slippage of friction materials) because it has no FM. Dex has a moderate amount, and ATF+4 has a high amount (that's why it's called a HFM ATF). I know of no ATF that uses increased amounts of FM to make it "less slippery". If you can provide any credible evidence of one, I'd be very interested in seeing it.