Originally Posted By: martinq
I don't think the shear will be significantly different between applications but the clutch material will be. Choosing a fluid to suit shift-behaviour is one aspect, durability, lubrication performance and flow are others.
I'd be curious to see if you notice a change going back to DW-1. Surprised to hear about the MaxLife but it's certainly possible.
Our Acura has the V-6 transmission with 92k miles on it, and our Honda has the I-4 transmission with 72k miles on it. My experience with fluids in these has varied. I will try to be brief.
We bought the Acura with 58k miles on it, from my parents. ATF was FF Z1. I did a 3 qt drain-and-fill with DW-1 at (I'm guessing) 70k miles. Great improvement. I did another 3d&f with DW-1 at around 75k miles. Shifting was even smoother. In hot weather, it was what I would classify as "too smooth". You couldn't feel it shift. On hot fluid on a hot day, it felt like it was slipping the 1-2 shift. Either the 1-2 shift was very slow, or the clutches were slipping and there was some significant torque management going on with the engine. So at around 80k or so, I 3d&f'd with MaxLife. Much better, much more positive shifting. Did another 3d&f with MaxLife at 85k. Although the MaxLife doesn't seem to deteriorate as fast as the DW-1 does, it still doesn't shift all that great. Some shifts are slow, some are firm...doesn't feel super consistent. At 90k, I 3d&f'd with the Castrol and like it so far. It seems a good compromise between the slippery-smooth DW-1 and the sometimes notchy MaxLife.
We bought the Honda with 46k miles on it, from a Honda dealer. They use MaxLife at that dealer (and Valvoline WB for motor oil). Transmission shifted extremely positive/firm. Just thought that's the way it was (I didn't know at the time that it had MaxLife in it). My in-laws bought a 2011 CR-V new. I drove it and the transmission shifted very smooth, and I wondered what was wrong with ours. I did a 3d&f with DW-1, much smoother. None of the slip-shifting as in the Acura. I went back to MaxLife in the Honda after my initial good impression of it in the Acura, and the Honda was back to shifting too firm. So I tried the Castrol and really like it. I've got two d&fs of Castrol in the Honda now. I tried the Castrol in the Acura because of how good it works in the Honda. No perceived degredation or change in shift behavior over time either.
So that's my story with various fluids in our Hondas. I might go back to DW-1 in the Honda. I had no issues with it in the Honda besides cost. I likely won't go back to DW-1 in the Acura, because of the poor shifting performance. Any comments/feedback are appreciated.