The valvoline stuff, like the rest of the stuff on the store shelf has a dry boiling point of 480, wet 311. The best I have found since starting this thread is Redline Brake fluid, which has dry point of 604 and 400 wet point. They claim this:
"Blendable with DOT 3, DOT 4 and DOT 5.1 fluids, RL-600 increases ABS cycle times for more responsive and consistent pedal feel".
As soon as brake fluid is put into the brake system, it absorbs water. Apply the brakes hard and some of that water will boil. The rider compensates by squeezing more on the lever. It is very possible to get to the point where squeezing more does...nothing! Also, the water is corrosive. In time, that Dot 4 fluid will turn (ie; have the same performance) as a DOT 3 fluid, and continue to spiral down. By starting with a higher performing fluid, I hope to be able to go longer with out a change (four years though, is too long).
Brake fluid is one of those things that you don't notice until you change it then you notice a big difference. In every vehicle that I have changed brake fluid, the brakes felt better, before, felt like a wood stick. The fluid in my daughters Toyota looked like an old urine sample and the brakes had an on/off feel before the change.
For those who have ancient brake fluid, I strongly suggest changing. You will notice that it takes less effort on the lever, better feel/progression. I just put on a new pr4 on the front and have some DP pads coming tomorrow. I want my bike to be tip top for spring/summer
