My 2000 Accord EX V6 has about 197000 miles on it. The transmission slips and bangs into gear frequently even under moderate acceleration; it has been doing so for about 8 or 9 years and has never become any worse in all that time.

When the problems first started I took it to two dealerships who both told me that I needed to replace the transmission. I couldn't afford that so I've just been waiting all this time for it to fail. Also, last week a reputable local transmission shop recently pulled a P0780 code and said that it needed to be replaced. I still can't afford it.

So after reading a great many posts here about replacing the ATF I figure it would be worth doing so if it would smooth out the shifting and decrease the slipping and banging. The experiences and opinions posted here (and on other forums) vary quite a bit as to whether replacing the ATF in an Accord with 197000 miles would improve the shifting or damage the transmission; maybe it's just a crapshoot.

I plan on using Valvoline Maxlife Full Synthetic ATF and adding 10 oz. of Lubegard Red (I saw this combination recommended here and on another forum).

I've also seen that flushing a high mileage transmission like mine is a bad idea.

So is using the cooling line method to replace ATF the equivalent of flushing the transmission?