Well I have had the D4 in my 2006 Camry SE for about one week now. Upon changing the original T-IV that had 26,000 easy miles, i was not very impressed by the amount of gunk and the dark brown color although no surprises as I have seen this fluid do much worse. With the Red Line D4 I no longer have harsh shifts from first to second anymore! I performed the cooler line flush and ran about 14 quarts through and also installed a magnefine in-line. Shifting is nice and smooth so we will wait and see what some miles on her will do. So far I am impressed by the D4.