Will a synthetic fluid help stop that anoy'n false neutral at stop lights on hot days?

No but a reflash will

Really, did you have this done?

False neutral?

I'm sure there is an "official term" for it, but that's what I call it. All 3 of my D/A have done this , the 01 and 03 were worse. I believe it was a weak spring in the converter that caused the fluid to drain out to fast and cause this condition. I thought it had been fixed on later versions. If you haven't experienced it, it's like the tranny doesn't stay fully engaged at any stop, when hot, normally in a lot of stop and go traffic. And doesn't fully re-engage till you've rolled a few feet, usually with a slight "clunk." I change fluid and both filters every 25,000 mi per manual so it's not a dirty filter and fluid starvation thing! :help2: