If you are switching to the Wilwood fluid to achieve the higher temperature rating, you need to flush the entire system out completely, and replace with your Wilwood fluid, otherwise you just wasted alot of money on the upgraded fluid. The 570 (technically 573) degree rating/boiling point is the "dry" boiling point...no contaminants, ie other fluid, moisture, etc..
Contaminated, the boiling point drops down to around 300 degrees.
Always best to check the wet (contaminated) boiling point, as no system is going to stay "dry" for very long.
Yes, 570 is a DOT 3 brake fluid