Hello, my wife has a 2005 Pontiac Montana SV6 6Cylinder with roughly 120,000 miles on it. I noticed while checking the fluids in it the transmission fluid was thin and watery I guess you can say. We have had the van for about 3 years now and I have never changed it and I have no idea if it has ever been changed. I have heard some people say that if it has never been changed then don't bother changing it because you are almost certain that the transmission will go south. Others have said, that is not true and an old wise man tale. So what are your thoughts on this? Its a good van and my wife really loves it so I need to make sure that it last for quite some time. I keep up on all of the other maintenance on it like oil changes and such. I am just curious about these different stories that I get. Also, if I do change it how many quarts does it take for a drain and fill? Thanks for your time.