Brake/Transmission Fluid questions

[Rutherford]

I live on a very steep long gravel road. The past two mornings while going down the mountain I have felt my brake pedal “drop” a small amount when the brakes are applied. To be more specific with the brake pedal depressed and held all the way down after a minute or so it has instantantly dropped a small bit more then hold. I gear down and do try to stay off the brakes as much as possible. Never felt any vehicle do this but I know ABS brakes can do some funny stuff. No warning lights have come on. The decent down the mountain is quite steep with lots of switchbacks. I had a wheel cylinder blow out on my pick-up one time going down thankfully near the bottom of the mountain. Lost pretty much all the hydraulic fluid very quickly. I have learned to carry an extra pair of shorts in that truck. Should I pack some in the Yaris? Maybe a speed sensor/ABS sensor issue? My 08 Yaris has 245,000 miles on it and is still going strong. The fact the car has held up so well considering it goes up and down this road where many need 4x4 is a statement about what these cars are made of. I DO NOT however like the arrogance or Toyota when there are issues. I think that will be their downfall, too bad because they do make a good car. I have a Jeep and have had more problems with it but Chrysler so far has made good on these without the attitude that Toyota has…..just my 2 cents.
One more thing. What are people’s thoughts about changing the lifetime automatic transmission fluid? Have not done mine. I have read some stuff about the new fluid may do more harm than good. My fluid is beginning to look a little dirty but not real bad.

[jack black]

drain and fill is OK, flush is a non-no on neglected trannies.