when your fluid is brown, your trans is on its way to its death. when you flush it everything that's floating in the brown fluid comes out, and that crap was all that was keeping your trans working. its all worn off clutch material. lose it and your car stops moving.
the best thing you could do for your trans is if you bought it new, or got it within 45,000 miles or less,( and if its still nice and red) is to flush it every 30,000.
did this with my 97 gmc, and that trans went 175,000 with towing a 4,000 lb boat every weather permitting weekend, snow plowing in the winter, and drove 3000 miles a month for work. and it could very well still be working to this day, the new owner made it into a landscaping truck, so its hard life continued.
