I switched on the basis that comptech and some other sources suggest that dex iii fluids may be used in honda autos to improve power holding and lower tranny temps. I had one drain/fill of straight M1 ATF, so 3/7, ~40% quarts in 03 I4 auto accord. Had it in about 5K miles until today, when my car did not seem to go into 5th gear at all. RPMs were always about 500 rpms too high on the freeway, either the torque converter lock up was not engaging or 5th gear wouldn't go in. After I got off the freeway, I turned the car off and on and it seemed to disappear. Problem did not reoccur for the rest of the day. Anyways, one strange problem is enough for me, I just did a drain/fill of Z1, so now <20% M1 in the tranny. Problem has yet to return, but will update if it does. I will probably drain/fill it again this weekend, bringing it down to <10%.