Originally Posted By: panthermike
Is there any validity to the claim that Honda's don't "like" non-OEM ATF's? Documented failures? Honestly curious, as I don't personally know of any trans failures with non-OEM ATF.
No, but both of ours have shifted noticeably different when on other fluids. I liked the MaxLife least in both transmissions, especially in our CR-V's transmission. Shifts were way too firm (harsh), the 2-3 upshift had an odd stumble sometimes, and the 1-2 shift would really drag on low throttle (like cruising through a parking lot). I understand that this is because the clutches are precisely timed with each other, where one disengages as the other engages to produce a smooth transition. When you change frictional properties of the fluid, that smooth transition is at stake. With a "stickier" fluid, that 1st gear clutch may not release as smooth as it should, and the 2nd gear clutch may not engage as smooth as it should, and you get weird transitions.
This PDF even mentions that the 1-2 shift feel relies heavily on OEM fluid, so aftermarket fluids aren't necessarily a go-to option (bottom of 2nd page):
http://www.sonnax.com/downloads/catalogs/sonnax-trans-report_v2n3.pdf
I like the Castrol Transmax IMV better than the MaxLife in our transmissions. The shifts seem smoother, though still not as smooth/fast as with DW-1. It's odd, even though DW-1 seems to produce the smoothest shifts, it also seems to produce the quickest shifts.
I personally get hung up with the additive package of Honda's OEM fluid. Both Z-1 and DW-1 now have used healthy amounts of zinc. To my knowledge, none of the universal fluids have zinc in them. I don't know why Honda uses the zinc, and I don't know what purpose it serves. I just know that it's in there, and they probably didn't just dump a zinc shaker into the drum because someone thought it'd be fun. I'm sure there's a reason for the zinc.
As you get more of the universal fluid in the transmission, the shift feel will likely change more and more. I have found this to be the case with both of ours. That said, I think some people are more sensitive to shift feel than others are. I feel very minute differences because I key-in on that stuff. Others may not feel the same thing. My disease is a blessing and a curse at the same time!