For my 190E 2.6 with 173k, Redline recommended their D4 ATF in place of Dextron lll. Redline stated it would increase the life of my transmission (my main concern) and NOT cause it to start leaking. Valvoline recommended that I use conventional Dextron lll and to avoid synthetic due to possibility of leaking due to increased cleansing. He also stated that NAPA ATF is identical to Valvoline. So...what to do?