I've owned this 06 Nissan Pathfinder for about a year now and right when I got it I changed the transmission fluid over to the red jug Valvoline maxlife full synthetic ATF. Before I changed the fluid everything seemed good and shifted fine but since I've changed the fluid over it seems to not be taking it so well. When the transmission is cold is shifts great like new but when the transmission reaches operating temperate I start to feel the shifts no clunks or extreme jerks or slips though. Also right at 45 mph the torque converter can't seem to figure out when to lock and unlock that's the most noticable thing. The transmission doesn't overheat I monitored the live data it's around 140-150°F when it starts acting up but never gets higher then that. The fluid is nice and clean and full on the dipstick. I also dropped the pan today to change the filter which was very clean a few specs but no chunks of anything. Magnets in the pan had minimal buildup for 129k miles. The fluid was changed by Nissan around 60k according to carfax. At this point I'm completely stumped... Have I killed another automatic transmission? I swear these things hate me... Is it the fluid? I've read many people using it with success I haven't found any Nissan 5 speed issues related to using it. Could this be something stuck in the valve body from the fluid change possibly knocking something loose? When I dropped the pan everything looked pretty dang clean except one bolt had a little bit of build up of something on it. Also that plastic junction pipe going to the heater cores decided to explode when I was topping off the transmission fluid at the car wash so I had to get it towed home.